Mint Mobile wifi calling won’t work on “hotspots”

After an interesting journey around the internet and various customer services I can report that Mint Mobile's "wifi calling" won't work for "hotspots" (like the mr-5100). This is due to Mint using T-mobile's infrastructure. Apparently wifi calling works fine with phones, tablets, watches - just not "hotspots". I swapped out for an ATT sim and am getting 35 to 50 Mbps down whichmis about 33 percent better than my old LTE M.O.F.I.