Netplay help

The new netplay version is acting weird. When I try to netplay with my sister, it simply says "failed to connect." However, when we play with someone on Anther's Ladder, it works for both of us. The last netply build worked perfectly fine between us. I have no idea why it wouldn't work for only us. I tried it with a third computer we had, and it didn't work with that one either. I would think it is something to do with our wifi as none of our computers can connect to each other while we can play with other people, but we tried to play with wifi somewhere else as well and it did the same thing. If anyone has any ideas I would be grateful.