I will add my $0.02.  I have an S10 Plus on AT&T Prepaid.  I purchased the phone while on vacation.  It worked great in NY and all the way to FL.  After returning home to SE Alaska, it all changed.  My prior phone worked great off our home WiFi.  This one, not at all.   I cannot make or receive telephone calls that can be understood and cannot send pictures via text or email at all when connected to WiFi.      I have tried both WiFi calling on and off.  I have checked for data saving settings.  I have gone in and cleared the cache.  I have reset the network settings.  I have done everything suggested above to no avail  In as much as we are in a poor area for AT&T reception, we cannot use the phone without a booster.  I am working on that.  In the mean time I need it to work on WiFi and I am very disappointed. ... View more