Fairphone 4 unable to connect to network after losing connection/reboot

I seem to have a problem on my phone where if I reboot my phone or lose connection by going underground then my phone will steadfastly refuse to reconnect to the network. The only thing that helps sometimes is leaving it off for a day or so then switching it back on and even that isn’t a sure way to fix the problem. Obviously this is a huge issue as I cannot actually use my phone as a phone.

This is on the latest version available for the Fairphone 4 and it also occurred on the previous version. This is different issue than I’ve faced previously where I’ve had to manually correct the APN settings, now I cannot even connect to a network to set the network. I’ve gone through all the standard troubleshooting steps, e.g checking roaming/mobile data is switched on, switching to 3g, etc. and nothing has fixed this.

Maybe it is worth to try from the APN page, top right 3 dot menu Reset default.

It may be best to do this while connected to reliable Wi-Fi, then straight after Reset default, switch to Airplane mode for 10 seconds and then try to return to mobile network.

Is this about APN?

If you mention your carrier and country maybe others have problems with the carrier (??).