on IPhone 8+ zoiper worked in a shopping mall free wifi, but at home it fails. both my Iphone 5s and Ipad work at home.
so if the 3 devices workin public wifi, then is it not logical to assume that the STUN server and its parameters are ok?
if 2 devices work thru the home wifi and its network , isn't it logical to assume that the ISP, the router, the network are ok?
conclusion is that Zoiper on the iPhone 8+ at home is not compatible with the home network.
with STUN disabled
REGISTRATION FAILED no DNS results (923)
i am clueless