LTE connection dropout during movement

I have a problem with my GL-XE300 router (I tested also Mudi). More specifically, with the GSM modem, the SIM card is registered correctly, it accesses the Internet. However, during movement such as driving, the modem practically breaks the connection every time when the Cell ID is changed (I have MullVad and Kill Switch enabled, but without that there is also this problem).
It looks as if when switching the base station, the connection to the GSM network is broken and the modem has to access the Internet again, which is practically impossible all the time when moving, for an hour of work, I access the Internet for maybe a total of 5 minutes.

Is there any advice for this?

I tested software version latest v4 and v3. and 3.2.18 work better.

Best Regards

Roaming between base stations should be a very basic behavior and should not break the connection.

Do you have any log without using vpn, as you said without vpn it also has problems?