How to connect to remote server?

I want to connect to a remote server.

Before this command worked perfectly :
ssh -i vpsMain

I need to connecto a other server on this VPS and beacause I’ve this error when I tried to connect it on VPS :`Provided Host header is not whitelisted“

I do this following command to add host of my server into whitelist of my remote server :

iptables -A INPUT -i eth0 -s ip addresse -j ACCEPT
iptables -A OUTPUT -o eth0 -d ip addresse -j ACCEPT

After this when I do telnet i’ve connection refused

So I wanted to remove iptables actions and do on the remote server :
iptables -P INPUT DROP

After this the remote server crash.
I now when I want to connect to it with this command :

ssh -i vpsMain doesn’t work and have this error :ssh: connect to host port 22: Operation timed out

Can someone help me?