Anyone else having Zoom issues like this?

We are having some real issues with Zoom calls. They mainly occur when we have more than 5 people on a call at the church. For example, we have had several staff meetings where 9 people are onsite and 50 are offsite. Everyone onsite reports a horrible connection and everyone offsite says their experience was fine except while trying to watch the participants at the church. Most ministries have now decided to host Zoom meetings from home to make sure they have good quality meetings. General video streaming seems to work fine and I rarely if ever have complaints about it. The issue happens inside and outside in all rooms all over the building. It also seems to happen with Teams as well.

Things that I have tried include: rebooting, different DNS, isp support calls on speed, Fortinet support calls (on speed and efficiency of the firewall, QoS policies set up properly, logging shut off, filtering shut off), 3rd party network colleagues with great advice, wifi QoS, researching the internet for similar issues but only found a few and they mostly suggested get a faster connection. Even with QoS on, it doesn’t seem to have helped and with traffic so low (only 9 users in the office) there isn’t much competition for priority anyway.

Our network:
We have a fiber internet connection at 1G/1G
We have a Fortinet firewall (about 5yrs old) that supports up to 400mbps throughput
Our wired speed tests are typically about 400mbps down and 600mbps up.
Wireless speed tests vary but are normally 100/200 on 5Ghz.
All switches are connected at 1G speeds and I can successfully verify that across the network on wired devices.

What would you do next if you were me?
Hire a Fortinet certified engineer?
Replace the firewall?
Am I forgetting something easy?
Has anyone else out there seen anything like this?

Thanks in advance for any and all suggestions. I am open to anything at this point.

What does “horrible connection” mean to your users, specifically? Audio cutting out, low video quality, etc.

Are all those users on WiFi?

It sounds to me like a contention/bottleneck issue of some form. If all your users are on WiFi, they will be contending for the same bandwidth, which will struggle for capacity. I would suggest two tests to run:

1/ run a bandwidth speed check ( on each offending device individually.
2/ run the same test on ALL internal machines simultaneously (e.g. trigger them all at the same time to force contention for bandwidth during the test)
3/ compare the above results. If this shows up a problem, then it should help you highlight where the internal contention issue is.
4/ if the above draws a blank, run a test Zoom call on all your offending internal devices adding on user at a time until you get the issue arise. At the same time, find a way to monitor the bandwidth through your router to see how much bandwidth is consumed per user. Do this test twice, once for all Zoom users on hardwire Ethernet connections and again with all Zoom users on your 5GHz WiFi.

Publish your results back here so we can advise further.

My suspicion is that Zoom may have a limit as to how much bandwidth they put to a given IP address. Thus if you have multiple Zoom users behind a single IP (as you will have behind your NAT firewall), then it may be necessary to send the results to Zoom to investigate further and make adjustments to their platform. However, before doing that you need to be certain it is not an internal networking issue.

Have you contacted Zoom support during the call? They pinpointed our problem to the exact piece of equipment having the issue when we had problems.

Support for free accounts is email so you might have to spend $15 and upgrade for a month.

Also, with Windows 10 we pause windows updates before every call and resume them after.

Try Webex?

Yes, freezing, hitchy video, audio cutting out, basically to where you can’t understand the participant.


Steve Hudson

I haven’t contacted them during a call because I am usually trying to participate myself but that is a good idea. We do have mostly Pro accounts.

I am also wondering if anyone has that many participants behind the same firewall? Or if there is some limit like what Russ mentioned. That does seem possible as well. I will look into that and see if we can get it raised if there is one. Good thoughts.

Our school has used Zoom with participants both on and off site, with less bandwidth than you have with no problems.

Several things come to mind:

  1. The firewall may be doing some App restrictions (not content filtering) that can interfere with software like this. Look under Proxy apps and under IM apps. I had to unblock something in IM to get Google Meet to work.
  2. If the users are on WiFi, the controller could be doing something to limit bandwidth per user or some application blocking.
  3. Try putting affected users on wired network, if that helps, problem may be in WiFi.

I doubt if the problem is overall bandwidth. I run an entire school on much less than that, and we have over 100 Chromebooks, plus teacher and staff computers, cloud based software, etc. and have bandwidth to spare.

  • Greg
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Thanks Greg. That is good to know. I do think it is firewall related. We have Proxy apps blocked. IM is allowed. I will look into that one a bit deeper.

I’m telling you, they could tell me what brand sound card the guy having trouble was using. They could tell he was on wifi when he lied and told me it was wired and they could tell it was downloading updates.

I just realized I never tied this up with a nice neat bow. I resolved this back in Spring but forgot to give an update here. The issue was for wired and wireless Zoom calls and we couldn’t get more than 7 on at a time for our whole network.

After trying to add every policy in the book for Zoom and Teams I had the issue narrowed down to the firewall hardware itself. I figured at 6 years old it was just a little long in the tooth even though it should have been able to handle the load. After upgrading to the latest model everything started working tremendously well. I think we have had up to 50+ Zooms call at one time now. The old model and the new model running the same firmware with dramatically different results. Thanks for all of the suggestions along the way.

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Hi Steve.
What make & model was your old router? Just curious as to its specification to get an idea of what other problems older routers might create.

@Russ Fortigate 100D, replaced by a 100F. Tremendous performance difference.

I’ve seen this before but it just sort of resolved itself!!