Because DCC chat does not work, this does not mean the shell is lagged.
Some things to check.
Are you able to send MSG commands "/msg <bot> op <password>"?
If yes:
Check the value of my-ip in the config file. The shell provider may have changed some settings and/or provider (yes the v-host may be the same, but the IP may have changed).
If no:
Check that the bot has a decient hsotmaks for you. IE "/msg <bot> ident <password>"
Does "/ctcp <bot> chat" work?
If yes:
Again, check the value of my-ip. Check with the shell provider if need be.
It could be a firewall issue. Check with the provider, as they may now be employing active blocking on most connections to prevent exploits remaining open.