In my experience with XA2 Ultra back when it had problems and currently with Xperia 10iii, the “works when moving the SIM to slot2” problems can also be solved by:
- turning on slot2 (even if it is empty)
- then turning off slot1
- then turning back on slot 1
- and now leave as-is (both slots on)
In that case, I don’t sacrifice my SD slot.
(and in my specific case, connection not working on the Xperia 10iii when roaming abroad, the problems got solved by flashing Android 11 / 62.0.A.9.11 with newsflasher, the reflashing Sailfish from a dd backup. Other people have also reported success with 62.0.A.3.107)