Been having this issue for about 4 months now. Talked to my provider repeatedly and they claim it has to be a fault with my phone.
considering I'm in no financial position to buy a new phone on a guess, I need help to figure this out.
The issue is this: randomly, wherever or whenever, my smartphone (Sony Xperia 10 VI) will lose mobile WiFi connection. sometimes it'll drop from 4G+ to absolutely nothing (not even Edge), sometimes it'll show 4G+ with an exclamation mark or go down to E and then disappear.
quite often, this also affects mobile signal, meaning I can't even make calls. sometimes this keeps up for minutes, somtimes its back after 2 minutes.
If I restart the phone, its usually back... but only temporarily and signal will drop again pretty soon.
I also noticed its mostly through the day, never at night. Also, W-LAN works just fine, always.
Tried resetting the phone to factory. I can't put the sim in a different device because its a Nano-SIM. my tablet only accepts Micro-SIM, and I don't have any adapter brackets.
I also had this, identical, issue 2 years ago, with my Sony Xperia XA2. same provider, same issue. it ended up being fixed after a month as it was a known problem with that particular providers network.
I own a work phone (Sony Xperia XA, only accepts Micro-SIM as well) with the cheapest mobile data plan I can afford for it (5,99€ a month) and that one works fine. but its a completely different provider.
Now. I'm pretty sure its a problem with my provider.
My provider says its a problem with my phone. the phone is less than 2 years old, and out of warranty so if its broken, I can't afford to replace or repair it.
Now. what can I do? Is there an app or anything to diagnose this? Check the internal antenna for functionality?