Forticlient losing dns after couple minutes

Hi
I have a strange behaviour of Forticlient. Not sure if this vpn client, or changes done by my company, or issue with my ISP.

Behaviour looks like this. Connecting to forti, everything is working fine.
Forti creating new resolv.conf in /etc and old one changing to resolv.conf.forticlient.backup
But after couple minutes resolv.conf is back to previous (this one from backup file) and I lose VPN functionality without disconnecting from vpn. Now I’m not sure what could be a reason for that, as earlier was fine, could be connected for hours. Then company made some changes on fortinet vpn, I have changed my isp to have quicker network.
I have second laptop with windows on it and forti on windows working without issue. so it’s my linux.
Any advise what to check, where to look for problem?