Hello there,

Problem first occured on August 28th 2023 - this was before the "New Teams" was introduced. This has remained a problem ever since.

User is able to SEND Teams calls normally. When RECEIVING a call, the user pick up the call, the call window pop up with just the grey background and shut off right after ("sorry, we couldn't connect you").

Teams version: Microsoft Teams 1.600.22378 (64 bits) (as of August. Our Teams is now updated, same issue)
Windows 10 22H2 x64

Tried:

- Rebooting Windows;
- Right-Click > Quit Teams, restart;
- Renaming %LOCALAPPDATA%\Microsoft\Teams & %APPDATA%\Microsoft\Teams to Teams_Old and restarting Teams;
- Uninstalling Teams machine-wide-installer & Teams user and reinstalling ("Teams for Work or School");
- Also tried reinstalling Teams machine wide installer; - Signed out of Teams, signed in to Teams with my own Teams 365 profile which is known to work. Same problem;
- Disabled "Integrated Camera" in DEVMGMT.MSC, answered the call, same problem (Camera is working on outbound calls normally anyway). See the log files attached.

It appears to be a problem related to our VPN, FortiClient EMS. If the VPN is disconnected, no problem. However, once the VPN is connected, picking up ONE call will work fine. Picking a SECOND (or third, or fourth), will fail with "sorry, we couldn't correct you". What sorcery is this? Disconnecting the VPN and reconnecting it will repeat this pattern, first call OK, second call fails. In any case, SENDING calls is never problematic. This occurs whenever I am connected on the office network contacting others remotely on the VPN. Also reproducible if I'm connected to the VPN and contact others on VPN too.

The problem started with a few users and has been spreading. If you're lucky, it will happen to you eventually, somehow. Many people were affected. The only workaround we have found is for each user, we simply create a new VPN tunnel from FortiClient, using the same remote gateway and port. It's a copy, however, this fixes the problem. Until someone else complains about that same thing again.

Here is a Teams support log (huge log, but all I did was place a few failing calls):
https://drive.google.com/file/d/11fC...usp=drive_link

I am puzzled.

Much appreciate if any leads,
Regards,