SSL-VPN DNS Issue (stops resolving after several hours), and OS Reboot required to fix

Hi,

I'm seeing a strange issue where Forticlient (SSL-VPN/thinner client) will work fine (connected to 80E), with internal staff being able to resolve internal Hosts without issue for several hours, and then suddenly DNS just stops resolving internal addresses. Connections via IP still work without failure though, and nslookups to the internal DNS server are ok.

The odd thing is, to fix the DNS issue, the OS (Windows 10 190x) needs to be restarted (even closing the client (shutdown) and relaunching the VPN doesn't work)

I've added DNS split tunneling for the specific domain [nnnnnn].local and will monitor - just wondering if anyone's run into this issue, and if so - is this a Windows update breaks all the things issue.