Microsoft Defender for Endpoint - Network Issues

Hello,

We recently started onboarding our machines into the Microsoft Security Center and using Defender for Endpoint. 

After doing so, we've noticed what seems to be related to how defender is handing network traffic.

Issue 1 - We have an on-premise file share. When accessing network shares we're unable to open files randomly. We'll get generic errors like "Sorry we couldn't find [File Name]. Is it possible it was moved, renamed or deleted? and "Microsoft Excel cannot access the file [File Name]. There are several possible reasons".

However, if we access the same files from a machine that has not been onboard yet there are no issues whatever so. 

Issue 2 - When accessing flow.microsoft.com from a machine with defender for endpoint enabled, I can not edit any flows or do any work. The flow constantly comes back as "invalid connection". I've deleted and re-added the connection multiple times, re-authenticated etc and nothing seems to work.

However, same situation as above. When I access flow.microsoft.com from a machine that has not been onboarded yet there are no issues editing or working with the flows. 

I've disabled EDR in Block Mode and also the Customer network indicators just to see if it would help but no luck. So far the only thing that works is offboard the device. 

Thanks.