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Hello! I need help. Here is the scenario:

One of our older classrooms - concrete block exterior walls, metal framed drywall interior walls - had real issues with WIFI propagation. We are a UniFi school so I used their heat mapping application and wandered around all the classrooms and hallways to find dead spots. Truly horrible results, so I then used the app to design new access point placements. This resulted in moving one access point and installing seven new access points.

Here is my issue: When I bring up the new access points every one of them gives the warning triangle and the message “Network look detected and blocked by Loop Protection”. Even if I disable EVERY access point, these ports still show the error. Powering down the port and bringing it back up does not resolve the issue. I have done everything I can think of to trace the loop to no avail. I will be resetting the switch itself at noon today (Eastern US) as a last ditch effort to find the problem.

I am really confused as to how I can have a loop on a port with the access point powered down?

Any help resolving this issue will put you at the top of the nice list.

Thank you,
Santa Michael

5 Spice ups
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I’m guessing this is a false-positive. Make sure your switch (and AP) firmware(s) are up to date, if it continues you might email their support for further help.

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Thank you Jay - everything is up to date. Hope to not have to contact their support.

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Keep us informed as to the reboot.

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Will do

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I have found that I needed to disable bpdu-guard on my switch ports where my WAPs are, otherwise they could disable the ports that my Uni-Fi WAPs were connected to.

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I will look at this. Interesting as I have not touched that so far. I have 87 other access points on site, none of the others are acting like this.

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I could not find that anywhere on my port config…

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The reset has cleared the loop on ONE Access point. However, I only had one active for testing. I am going to turn another one on to see what happens. Crosses fingers!

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All access points are up and running with no loops detected. When in doubt, reset the switch. Got it.

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came here to say the same

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It’s not every device that puts the port into err-disable. It seemed to only happen when the WAP lost access to the controller for a while, which would happen when I took my WAN device offline for 30 minutes.

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I see that you’ve resolved your issue, but I’ve found that if your UniFi APs are hardwired it’s good practice to disable meshing on them. Meshing can cause network loops in UniFi networks.

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+1 for this.

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Thank you! That was the first place I went as the previous tech had several meshed AP’s. I pulled cable to them all and eliminated that issue first thing.

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Where do you find this? Can you give me a screenshot?

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FWIW I occasionally see new APs do this, but it normally clears itself within a few minutes

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Thank you - I let it tun overnight for convergence. No dice. It’s all good now - so far anyway!

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Nice you got it working.

A weird thing with AP’s and switches, if you unplug an AP and plug it into a different port, the switch can send a packet addressed to another AP out that port..and since AP’s can route traffic, it will hand it to the AP that used to be on that port, which will send it back to the switch…now it looks like a loop to the switch.
Ideally, the switch should eventually figure this out, but switches can be weird sometimes…

tldr…reset switches when moving things that route traffic

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