There are a couple different ways you can connect to more than one IRC server. It all depends on if you want to always reconnect to the initial server or if you’re only connecting once.
Method 1: If you want to connect to another server on the fly, meaning once you close mIRC it will not reconnect to this server.
/server -m irc.theserver.com:6667
Method 2: Using the Remote feature in mIRC will allow you to reconnect to more than one server every time you open mIRC and the process is automatic, unlike the above.
Click Tools -> Scripts Editor… Now under the Remote tab add the following in the box:
on *:start: {
server irc.theserver.com:6667
server -m irc.theserver.com:6667
}
Repeat the server -m line to add more servers.