I have an unlocked att lumia 950, using it on tmobile

[Windows Central Question]

I have an unlocked att lumia 950, using it on tmobile, i need APN settings so i can use internet and mms. Please help. Tmobile techs werent able to do it.Can only use internet over wifi and can only receive mms, i can not send mms. Text and calls and internet over wifi is fine. Please help.