Super odd issue with UI enterprise switches connecting to cisco core switch

Hey guys hopefully this is the right place to ask.

I moved one of my locations to use UI enterprise 48 POEs to do layer 2 and POE duty then a Cisco switch to do the rest, vlans, dhcp, etc. a dns server and a pfsense firewall to do firewall and wan connection duties. As well as moving from Extreme APs to U6 enterprises APs.

here’s a rough diagram of the network in question :

the issue that i am seeing is that every time i make a wifi network change, or adopt devices wifi for whatever reason just stops working (only wifi, wired devices keep working perfectly fine), dhcp stops handing IP addresses, and the only way to fix it, is quite easy actually, is to unplug and plug the uplink connection from the cisco to the UI switches.

So i was wondering is anyone has any idea on what could be, or maybe im missing something simple. If any more info is needed please let me know :slight_smile:

Thank you in advance!

I would looks for logs in the Cisco and try to ping the devices on the WiFI from the pfsense and then from the Cisco.

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cant ping the devices on wifi because they all drop when changes are saved. Then when they try to re-connect they just grab a link local address. APs however work just fine and can be pinged from cisco and the PFsense. I will look through cisco logs. Is just throwing me for a loop given the change shouldn’t affect anything below the unifi gear.

question for you Tom, is it expected behavior for WiFi devices to drop when making changes to the WiFi settings in unifi? for example when this last happened, it was because i had to create a temporary SSID, when i made that change devices dropped for about 5 seconds then came back up normally, it was when i went to delete that SSID that the devices dropped and did not come back until i unplugged and plugged the cisco to unifi up-link.

Thank you so much for replying Tom, big fan!

When you change SSID those changes will cause the UniFi to drop connections as it restarts the service to add the new SSID.

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will update OP, but I think i might have found the issue. Digging around, and asking, some people had issues when not setting STP/RSTP. So i did configure it, cisco as 0 and the subsequent switches down the line 4096, 8192, 12288.

Also, i completely forgot to shut down meshing on my APs given they are all wired and the wireless meshing is not needed.

We’ll see what happens.