Multiplayer TBD NAT issues

[IdleFire Guardian]

A friend of mine can connect to my game with no issue however it does not allow me to join their game. For me it says they are on TBD NAT while I'm TBD NAT (which is the same thing), with a thing below with "BSH" which I'm not sure if that makes any sense. I can't really think of any details to say aside from it allows me to join for like 10 seconds and then kicks me. Switching my network quality from medium to ultra did not change the results.
How do we solve this issue?

[SPC. Cleep]

I have the same issue but sadly I don't have a solution. Please let me know if you find a fix for it.