Weakening mobile data signal strength

[brbailey]

I have four phones / sims in the family. The quality and strength of data signal has deteriorated across all devices dramatically. What was 4G is now 3G and 1 bar at home, for example. I've spoken to sky and reset network configuration and followed multiple instructions including ensure software is up to date. Is this a known issue? I know sky mobile is o2 and they are generally inferior to the competition. But is anyone else experience a deterioration of data signal strength? Any known fixes? I've been advised to upgrade my phone. That obviously won't work (I've been 'upgraded' to 5G but that makes not difference to experience at home - inside or outside the house when I used to benefit from 4G full bars). 

[DB641]

I've also found this problem, with my service. I used to be with O2, before switching to Sky and places I used to get good service, is either weaker or none existent. I can stand next to the new 5G masts and only get 4G, which isn't good. So to me either O2 or Sky are throttling the service to our phones. 

[SRM2024]

In exactly the same position with multiple devices. I cannot access most things that require internet. It's beyond frustrating.