When me and my roommate try hoping into a lobby together, one of us gets timed out kicked for inactivity.
if we play separately then everything is dandy . also if one of us connects to a hotspot then we are able to play together.
we are using the T-Mobile home internet (there is no ISP where we stay).
You are both showing the same external IP, which isn't going to work so well. You can use a VPN, get a static IP, or try configuring UPnP (can't say if UPnP will work).
there is no ISP where we stay
There is always an ISP. It's whoever is providing you internet service. T-Mobile in your case.
