from a dos box (start/run/CMD/ok) type IPCONFIG

or from mirc itself type these commands with 2 seconds between each one
//localinfo -h
//echo ip is $ip
//localinfo -u

PS: if you end up being able to send but not resume files, try chaning the IRC server port to 7000, dlinks have some built in port remapping for dcc but itrs not very good, chaning irc server ports to 7000 disables this remapping, leavinbg it to u and your router settings.