Another update, after continuing analysis on the WebShield it seems it's actually caused by Microsoft. There are known issues in build 14936 of Win10. Microsoft knows about it and is working on a fix.
This is not something unique to SecureLine. Cisco anyconnect corporate VPN is also experiencing similar issues (as I know from personal experience) so it's an issue inside Win10 that is causing the issue.
Stay tuned for further updates on this topic.
Thanks,
Davidek