O365 Connection issues using Tunnel 1.0

Nicely said,

I can absolutely spin up another post for these discussions, as I am sure others are having the same issues as us.


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This topic is a continuation of the conversation Periodic Issues Connecting to O365 with Teams and Outlook clients in which we determined that migrating to Tunnel 2.0 is the best solution.

However, in some cases migrating is not an option. This thread is aimed to have conversations that will hopefully yield to a workaround under Tunnel 1.0



Thank you for starting this thread up. I will be able to post a summary of everything our team has tried already in hopes another company can chime into assist with the issues we have been experiencing.

TLDR of the other post: During rollout of zscaler in our environment, we have had random issues only for remote workers where teams and outlook fail to connect, and are unable receive any network communication. The issue is only present when Zscaler and Global Protect are both running. Turning off ZCC does not fix the issue, but logging out of ZCC immediately fixes the issue for most, but a disconnect and reconnect from global protect fixes the rest. Once zscaler is turned back on for the broken users, the issue comes back. The only permanent fix has been to remove zscaler entirely. Excluding Teams and outlook traffic from the Pac also did not provide 100% help for users.

We have tried Reinstall of ZCC, Reinstall of Global Protect, reboot, PCAP’s of Loopback, Tunnel 1.0 best practices for PC (Disable loopback restriction, IPv4 over IPv6, Override WPAD, Packet filter based), Fiddler (nothing exciting). Our current running theory is that the traffic is getting stuck on the loopback adaptor somehow, but have not yet found a way around this restriction.

Is anyone else having these issues still? We will post a full document overviewing this during the business work week, but I wanted to get something out to begin the thread. Thanks!