As an aside I found this old 2022 thread yesterday that seemed to describe the same or similar issue - but no resolution I could see at that time?
EDIT: Further update on this (events Friday 10 October my time) - the internet access continued to experience a couple of unexplained black outs to access - for no apparent reason - and happened across all interfaces (wi-fi, regardless of what WLAN I’m on, and both my SIMs, so all 3 interfaces simultaneously - but note no VPN, as I have uninstalled that to eliminate it as a cause).
Two new or different things however were (in no particular order):
- I did not get the exclamation mark warnings on the 2 SIM and the Wi-Fi icons at top right of the phone home screen, and
- The access just ‘rematerialised’ after about 10-20 minutes each time without me doing anything (i.e. I didn’t reboot or do anything else, I just left the phone and checked in my browsers again sometime later if they had access).
As I’ve previously had vaguely similar issues on my Linux PC (continuous lack of internet access for no reason), that I attribute to ProtonVPN and it’s kill switch function (even after uninstalling), I would like to investigate my phone network stack and settings in more detail. But as I’m not overly familiar with Android, and haven’t found any useful guidance a little stalled in that area. I can easily see in the wi-fi connection details the DHCP data and if it has a valid gateway, DNS servers, etc; but can’t see those details for the cellular data (SIM) connections that I can find; and not sure where i can verify what the phone is actually using (on my PC I found even though it had DHCP info it wasn’t using all of it, only the IP address being issued, so it had no or invalid DNS server addresses and gateway address - which I attributed to the VPN for lack of any other obvious cause).