Just posting a "me too" I work for a Fortinet VAR and have not had luck with Fortinet help. My issue does affect zoom for some customers as well, though.
What kind of switching and wireless are you guys running; my firewall/FortiExpert keeps saying there's no way it's the firewall, but I haven't seen proof. We get the complete hang up as well as some quality issues; but i have packet captures that shows that inbound/download UDP traffic will literally stop for multiple seconds for the call traffic; but TCP traffic from the same source/dest IP at the same time doesn't seem affected. Honestly I don't see how this is not a firewall issue at this point; but I'm getting push back and next to zero help from the firewall perspective so it's up to me to prove something one way or the other.
the "remote" users on the calls can see/hear the on prem user just fine during the hang; which the packet capture also represents. Is this consistent with what you notice?
I have several customers affected as well as us ourselves.
I have customers with Fortigates that are affected and some that are not; seems to creep up randomly. I have seen this on 6.0.4 (upgrading this customer this weekend to 6.0.9) I have seen it on 6.2.3 as well, and Im hesitant to put anything on 6.2.4 based on what i've heard.
I believe one very specific pattern I've seen so far (but not necessarily the case) is that this is happening in HA units.
One customer was a brand new 600E HA pair and the box itself was the problem; got the box replaced; but I am still seeing this in networks where I can flip the cluster over and still have an issue.
Did either of you get anywhere with this? I have dozens of hours into this, and I don't care if the problem is the firewall or not; I need proof of where in the network this is occurring.