I am sad to hear that. I used my X, XA2 and now my 10 III as daily drivers from day one in 2017. There were some issues but overall I could rely on my phones. The screen of the X broke and GPS antennas on the XA2 lately degraded so much, that it became my new phone for things I won’t do with a device I have personal data on.
Mobile data issues seem to be a problem for some people. My 10 III sometimes needs a few seconds to switch from WiFi to mobile data but that is it then.
Dual SIM, SIM in slot one, SD in the other, both slots active (!) and standard settings from Vodafone.
I never had two SIMS, though and I my experience is limited to a bunch of European countries.
God luck with your experiments. I hope you’ll get everything up and running soon.