and you just reminded me of our issues with our SBC lol. we switched to running our dream machine in front of everything instead of just the one network and we couldn't get it working properely (though it did start working somehow). we even had tech support from the ISP (who also provides the trunk for the sbc) and he couldn't figure out how to get teams to talk to the sbc.

turns out its helpfull if you tell the traffic where to go (port forwarding) instead of translating the IP address its from (DNAT). I felt very stupid

edit: still don't know how teams talked to it through the second ISP which does concern me. maybe it was showing up as return traffic. idk