Based on more experiments we do conclude that it is, in a way, possible to configure this using settings for SIM Switching. It seems as if SIM Management - SIM Switching - Check interval is used to determine if connection is "good" when switching back. But the setting is used without retry attempts.
The inital setting (30 secs) is too short for the Telia card to get a connection. Changing this to 120 secs was a workaround.
Right now we go with:
- Enable automatic switching
- Check interval 120
- SIM1 to SIM2: On data connection fail, method ICMP echo, ICMP host 126.96.36.199, timeout =3 Attempts before SIM failover = 3
- SIM2 to SIM1: Initial timeout = 5, subsequent timeout = 5