SSH Tunnel - Connect from local to remote server

I am running on my VPS Ubuntu 20.04.1 LTS and locally Ubuntu 18.04.3 LTS and I want to create a ssh-tunnel to connect to my database to run SELECT's for reporting in my laravel 6 application.

My production database has the following version:

> mysqld --version
/usr/sbin/mysqld  Ver 8.0.23-0ubuntu0.20.04.1 for Linux on x86_64 ((Ubuntu))

And I connect with the following credentials from my local to my remote server:

DB_HOST_PROD=127.0.0.1
DB_PORT_PROD=13306
DB_DATABASE_PROD=test_db
DB_USERNAME_PROD=root
DB_PASSWORD_PROD=prod_pwd

My mysql db config looks like the following for SHOW VARIABLES LIKE '%time%';:

binlog_max_flush_queue_time	0
connect_timeout	90
default_password_lifetime	0
delayed_insert_timeout	300
explicit_defaults_for_timestamp	ON
flush_time	0
have_statement_timeout	YES
innodb_flush_log_at_timeout	1
innodb_lock_wait_timeout	50
innodb_old_blocks_time	1000
innodb_rollback_on_timeout	OFF
interactive_timeout	300
lc_time_names	en_US
lock_wait_timeout	31536000
log_timestamps	UTC
long_query_time	10.000000
max_execution_time	0
mysqlx_connect_timeout	30
mysqlx_idle_worker_thread_timeout	60
mysqlx_interactive_timeout	28800
mysqlx_port_open_timeout	0
mysqlx_read_timeout	30
mysqlx_wait_timeout	28800
mysqlx_write_timeout	60
net_read_timeout	90
net_write_timeout	90
original_commit_timestamp	36028797018963968
regexp_time_limit	32
rpl_stop_slave_timeout	31536000
slave_net_timeout	60
slow_launch_time	2
system_time_zone	CET
time_zone	SYSTEM
timestamp	1614464427.484124
wait_timeout	300

When running my ssh-command I get:

admin@admin-VirtualBox:~$ /usr/bin/ssh -o StrictHostKeyChecking=no -v -v -v -N -i /home/admin/.ssh/id_rsa -L 13306:127.0.0.1:3306 -p 22 [email protected]
OpenSSH_7.6p1 Ubuntu-4ubuntu0.3, OpenSSL 1.0.2n  7 Dec 2017
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: resolving "xx.xx.xxx.xxx" port 22
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to xx.xx.xxx.xxx [xx.xx.xxx.xxx] port 22.
debug1: Connection established.
debug1: identity file /home/admin/.ssh/id_rsa type 0
debug1: key_load_public: No such file or directory
debug1: identity file /home/admin/.ssh/id_rsa-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.6p1 Ubuntu-4ubuntu0.3
debug1: Remote protocol version 2.0, remote software version OpenSSH_8.2p1 Ubuntu-4ubuntu0.1
debug1: match: OpenSSH_8.2p1 Ubuntu-4ubuntu0.1 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to xx.xx.xxx.xxx:22 as 'root'
debug3: hostkeys_foreach: reading file "/home/admin/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/admin/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys from xx.xx.xxx.xxx
debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected],zlib
debug2: compression stoc: none,[email protected],zlib
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256
debug2: host key algorithms: rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected]
debug2: compression stoc: none,[email protected]
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:aaaaaaaaaaaaa/aaaaaaaaaaaaaaaaaaa
debug3: hostkeys_foreach: reading file "/home/admin/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/admin/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys from xx.xx.xxx.xxx
debug1: Host 'xx.xx.xxx.xxx' is known and matches the ECDSA host key.
debug1: Found key in /home/admin/.ssh/known_hosts:1
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug1: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey after 134217728 blocks
debug2: key: /home/admin/.ssh/id_rsa (0x55f736df0320), explicit, agent
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,[email protected],ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected]>
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey,password
debug3: start over, passed a different list publickey,password
debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering public key: RSA SHA256:aaaaaaaaaaaaaaaaaaaaaaaa /home/admin/.ssh/id_rsa
debug3: send_pubkey_test
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 60
debug1: Server accepts key: pkalg rsa-sha2-512 blen 279
debug2: input_userauth_pk_ok: fp SHA256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
debug3: sign_and_send_pubkey: RSA SHA256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
debug3: send packet: type 50
debug3: receive packet: type 52
debug1: Authentication succeeded (publickey).
Authenticated to xx.xx.xxx.xxx ([xx.xx.xxx.xxx]:22).
debug1: Local connections to LOCALHOST:13306 forwarded to remote address 127.0.0.1:3306
debug3: channel_setup_fwd_listener_tcpip: type 2 wildcard 0 addr NULL
debug3: sock_set_v6only: set socket 5 IPV6_V6ONLY
debug1: Local forwarding listening on ::1 port 13306.
debug2: fd 5 setting O_NONBLOCK
debug3: fd 5 is O_NONBLOCK
debug1: channel 0: new [port listener]
debug1: Local forwarding listening on 127.0.0.1 port 13306.
debug2: fd 6 setting O_NONBLOCK
debug3: fd 6 is O_NONBLOCK
debug1: channel 1: new [port listener]
debug2: fd 3 setting TCP_NODELAY
debug3: ssh_packet_set_tos: set IP_TOS 0x10
debug1: Requesting [email protected]
debug3: send packet: type 80
debug1: Entering interactive session.
debug1: pledge: network
debug3: receive packet: type 80
debug1: client_input_global_request: rtype [email protected] want_reply 0
debug3: receive packet: type 4
debug1: Remote: /root/.ssh/authorized_keys:1: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
debug3: receive packet: type 4
debug1: Remote: /root/.ssh/authorized_keys:1: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
debug1: Connection to port 13306 forwarding to 127.0.0.1 port 3306 requested.
debug2: fd 7 setting TCP_NODELAY
debug2: fd 7 setting O_NONBLOCK
debug3: fd 7 is O_NONBLOCK
debug1: channel 2: new [direct-tcpip]
debug3: send packet: type 90
debug3: receive packet: type 91
debug2: channel 2: open confirm rwindow 2097152 rmax 32768
debug3: receive packet: type 96
debug2: channel 2: rcvd eof
debug2: channel 2: output open -> drain
debug2: channel 2: obuf empty
debug2: channel 2: close_write
debug2: channel 2: output drain -> closed
debug2: channel 2: read<=0 rfd 7 len 0
debug2: channel 2: read failed
debug2: channel 2: close_read
debug2: channel 2: input open -> drain
debug2: channel 2: ibuf empty
debug2: channel 2: send eof
debug3: send packet: type 96
debug2: channel 2: input drain -> closed
debug2: channel 2: send close
debug3: send packet: type 97
debug3: channel 2: will not send data after close
debug1: Connection to port 13306 forwarding to 127.0.0.1 port 3306 requested.
debug2: fd 8 setting TCP_NODELAY
debug2: fd 8 setting O_NONBLOCK
debug3: fd 8 is O_NONBLOCK
debug1: channel 3: new [direct-tcpip]
debug3: send packet: type 90
debug3: channel 2: will not send data after close
debug3: channel 2: will not send data after close
debug3: receive packet: type 97
debug2: channel 2: rcvd close
debug3: receive packet: type 91
debug2: channel 3: open confirm rwindow 2097152 rmax 32768
debug3: channel 2: will not send data after close
debug2: channel 2: is dead
debug2: channel 2: garbage collecting
debug1: channel 2: free: direct-tcpip: listening port 13306 for 127.0.0.1 port 3306, connect from 127.0.0.1 port 34636 to 127.0.0.1 port 13306, nchannels 4
debug3: channel 2: status: The following connections are open:
  #2 direct-tcpip: listening port 13306 for 127.0.0.1 port 3306, connect from 127.0.0.1 port 34636 to 127.0.0.1 port 13306 (t4 r0 i3/0 o3/0 fd 7/7 cc -1)
  #3 direct-tcpip: listening port 13306 for 127.0.0.1 port 3306, connect from 127.0.0.1 port 34640 to 127.0.0.1 port 13306 (t4 r1 i0/0 o0/0 fd 8/8 cc -1)

debug3: receive packet: type 96
debug2: channel 3: rcvd eof
debug2: channel 3: output open -> drain
debug2: channel 3: obuf empty
debug2: channel 3: close_write
debug2: channel 3: output drain -> closed
debug2: channel 3: read<=0 rfd 8 len 0
debug2: channel 3: read failed
debug2: channel 3: close_read
debug2: channel 3: input open -> drain
debug2: channel 3: ibuf empty
debug2: channel 3: send eof
debug3: send packet: type 96
debug2: channel 3: input drain -> closed
debug2: channel 3: send close
debug3: send packet: type 97
debug3: channel 3: will not send data after close
debug1: Connection to port 13306 forwarding to 127.0.0.1 port 3306 requested.
debug2: fd 7 setting TCP_NODELAY
debug2: fd 7 setting O_NONBLOCK
debug3: fd 7 is O_NONBLOCK
debug1: channel 2: new [direct-tcpip]
debug3: send packet: type 90
debug3: channel 3: will not send data after close
debug3: channel 3: will not send data after close
debug3: receive packet: type 97
debug2: channel 3: rcvd close
debug3: channel 3: will not send data after close
debug2: channel 3: is dead
debug2: channel 3: garbage collecting
debug1: channel 3: free: direct-tcpip: listening port 13306 for 127.0.0.1 port 3306, connect from 127.0.0.1 port 34640 to 127.0.0.1 port 13306, nchannels 4
debug3: channel 3: status: The following connections are open:
  #2 direct-tcpip: listening port 13306 for 127.0.0.1 port 3306, connect from 127.0.0.1 port 34654 to 127.0.0.1 port 13306 (t3 nr0 i0/0 o0/0 fd 7/7 cc -1)
  #3 direct-tcpip: listening port 13306 for 127.0.0.1 port 3306, connect from 127.0.0.1 port 34640 to 127.0.0.1 port 13306 (t4 r1 i3/0 o3/0 fd 8/8 cc -1)

debug3: receive packet: type 91
debug2: channel 2: open confirm rwindow 2097152 rmax 32768
debug3: receive packet: type 96
debug2: channel 2: rcvd eof
debug2: channel 2: output open -> drain
debug2: channel 2: obuf empty
debug2: channel 2: close_write
debug2: channel 2: output drain -> closed
debug1: Connection to port 13306 forwarding to 127.0.0.1 port 3306 requested.
debug2: fd 8 setting TCP_NODELAY
debug2: fd 8 setting O_NONBLOCK
debug3: fd 8 is O_NONBLOCK
debug1: channel 3: new [direct-tcpip]
debug3: send packet: type 90
debug2: channel 2: read<=0 rfd 7 len 0
debug2: channel 2: read failed
debug2: channel 2: close_read
debug2: channel 2: input open -> drain
debug2: channel 2: ibuf empty
debug2: channel 2: send eof
debug3: send packet: type 96
debug2: channel 2: input drain -> closed
debug2: channel 2: send close
debug3: send packet: type 97
debug3: channel 2: will not send data after close
debug3: receive packet: type 97
debug2: channel 2: rcvd close
debug3: receive packet: type 91
debug2: channel 3: open confirm rwindow 2097152 rmax 32768
debug3: channel 2: will not send data after close
debug2: channel 2: is dead
debug2: channel 2: garbage collecting
debug1: channel 2: free: direct-tcpip: listening port 13306 for 127.0.0.1 port 3306, connect from 127.0.0.1 port 34654 to 127.0.0.1 port 13306, nchannels 4
debug3: channel 2: status: The following connections are open:
  #2 direct-tcpip: listening port 13306 for 127.0.0.1 port 3306, connect from 127.0.0.1 port 34654 to 127.0.0.1 port 13306 (t4 r0 i3/0 o3/0 fd 7/7 cc -1)
  #3 direct-tcpip: listening port 13306 for 127.0.0.1 port 3306, connect from 127.0.0.1 port 34658 to 127.0.0.1 port 13306 (t4 r1 i0/0 o0/0 fd 8/8 cc -1)

admindebug3: receive packet: type 96
debug2: channel 3: rcvd eof
debug2: channel 3: output open -> drain
debug2: channel 3: obuf empty
debug2: channel 3: close_write
debug2: channel 3: output drain -> closed
debug2: channel 3: read<=0 rfd 8 len 0
debug2: channel 3: read failed
debug2: channel 3: close_read
debug2: channel 3: input open -> drain
debug2: channel 3: ibuf empty
debug2: channel 3: send eof
debug3: send packet: type 96
debug2: channel 3: input drain -> closed
debug2: channel 3: send close
debug3: send packet: type 97
debug3: channel 3: will not send data after close
debug3: receive packet: type 97
debug2: channel 3: rcvd close
debug3: channel 3: will not send data after close
debug2: channel 3: is dead
debug2: channel 3: garbage collecting
debug1: channel 3: free: direct-tcpip: listening port 13306 for 127.0.0.1 port 3306, connect from 127.0.0.1 port 34658 to 127.0.0.1 port 13306, nchannels 3
debug3: channel 3: status: The following connections are open:
  #3 direct-tcpip: listening port 13306 for 127.0.0.1 port 3306, connect from 127.0.0.1 port 34658 to 127.0.0.1 port 13306 (t4 r1 i3/0 o3/0 fd 8/8 cc -1)

I am running locally my development database on:

DB_HOST=127.0.0.1
DB_PORT=3306
DB_DATABASE=test_db
DB_USERNAME=root
DB_PASSWORD=local_pwd

The error I get in my application is that MySQL server has gone away.

It seems that the ssh tunnel is properly created, however it also seems that the data cannot be queried and provided via the tunnel. However, I am unsure if it is the firewall or a mysql use authorization issue or ...?

To be honest I have no idea how to further narrowing the problem space or how to debug further to find the real problem.

I really appreciate your reply!