Laravel Forge setup connection between servers to access redis

You need to tell it which network adapter Redis needs to listen on in order to listen to the private network. By default it only listens to requests from its own server.

Try adding changing the bind setting to bind <private_ip> in the /etc/redis/redis.conf file, where <private_ip> is the private address of the redis server. Then it will listen to requests being sent to that ip, which will be those servers that have access to the private ip.

That doesn't help. I changed the following in /etc/redis/redis.conf:

#bind 0.0.0.0 -::1
bind 10.0.0.5

Then restarted redis via sudo systemctl restart redis. Same output as before:

redis-cli -h 10.0.0.5 -p 6379
10.0.0.5:6379> PING
(error) DENIED Redis is running in protected mode...

Solved it by resetting it to bind 0.0.0.0 -::1 and setting a password in the redis.conf

After you first create the cache server, you need to create a password for it: click the "Databases" section for your cache server, and set a password there. Then, for the server that needs to connect to it, make sure the REDIS_HOST is the private IP of your cache server, and REDIS_PASSWORD is the password that you just set.

Aside from that, check the "Network" section of your servers to make sure that they can connect to each other as-needed.

Hope that helps!