VPN disconnects internet

Hi,

We have a pretty stable IPsec VPN setup to enable +/- 20 remote clients to connect through forticlient to the main office. However, there is 1 computer with a very annoying problem: When connected with VPN, the computer is disconnected from the internet. I have tried everything like changing the remote subnet to avoid conflicts, disabled remote gateway relays on the forticlient network adapter, configured static DNS (internal and failover to external dns)...  

The strange thing is that this issue does occur regularly, but sometimes everyting works fine.

(Computer runs Win10Pro)

Does anyone have clue what the problem could be?

Thanks in advance!