Just to report the same ongoing fault with the Nokia 3.1:
My wife and I both have Nokia 3.1s, updated to Android 9 & all security patches. We both lost data roaming in the EU (home is UK) in about May 2019 - previous to that they had roamed perfectly.
On my phone I have had 3 long phone calls with Tesco (the provider), and an online chat with Nokia. No progress. No data roaming in France or the Netherlands, though voice & SMS function abroad. No problems when at home.
To summarise what I have tried (and yes - I do know how to enable data roaming when abroad) with total failure even though I get perfect 4g/3g when at home. Some of these are clearly unnecessary for a phone that gets mobile data at home - but I did them anyway:
- restart phone
- flight mode on/off
- reset Wifi, Mobile & Bluetooth
- manually select network
- retype and select APN as provided by Tesco
- SIM out, wait, polish SIM, SIM in
- put in French SIM while in France - perfect 4g; this is not roaming but shows that the phone understands French frequencies etc
- put my SIM in a friend's Samsung phone when abroad - perfect roaming 4g
- put friend's SIM (that roamed perfectly from his Samsung phone when abroad) in my phone while abroad -> no mobile data
- Tesco did some sort of account reset that required me to restart the phone -> still no data roaming. For each phone call they checked that I had not exceeded data abroad limits.
- Factory reset phone and no apps reinstalled: no data roaming.
The SIM status page when abroad shows everything normal for Service Status, Signal Strength, Mobile voice 4g, Mobile data 4g, Roaming BUT Mobile Network State shows 'Disconnected' (this is 'Connected' at home).
Logically this looks like some sort of OS bug, installed sometime about May 2019.
Any further ideas would be appreciated. If this were a Linux computer I'd run a lot of diagnostics - but I have no idea how to do this on Android.