To sort out port forwarding, read the manual
If you have a firewall it should have some sort of help file, look in the directory the firewall was installed for. If it's a hardware router than it should have come with a manual - you should also find help on the manufacturer's website, aswell as contact information to seek help from the professionals.
There isn't a place in mIRC or on your computer to tell you if your mIRC ports are set up correctly. You need to check the settings of any firewalls/routers you have (see above) and check which ports, if any, are forwarded. The same port "range" (the lowest and highest port number) needs to be set in DCC options.
So, if ports 1234
, 1235, 1236, 1237 and 1238
were forwarded, the range is 1234-1238
To access the mIRC DCC port settings, you need to press ALT+O
go to Connect
(press the '+' if the menu's not expanded) and go to Options
under Connect. Then click on the Advanced
button. Another way to say this is like I said in my last post:ALT+O > Connect > Options > [Advanced]
In the end you should end up with this: