Do you have a lan cable at all? Even a short one for a temporary test might help.

The fact you can play uninterrupted and she can't on the same network makes me think it's her nic. Or your router is forwarding ports to your computers ip and thus she isn't receiving them.

If you have a lan cable try that even if its impractical as a long term solution it would at least eliminate some of the possibilities and point to the Intel wireless nic