Wireless chaos after disconnecting cable at router (two APs)

ColdCase

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I tried to search but no luck, dunno exactly what to search for. I’ve been using a Time Machine AEXT for the home wireless network for what seems like a decade. I added a UniFi AC Pro wireless access point to improve coverage to the far bedrooms and basement. I did this by setting the new AP's SSID to the existing AEXT SSID. The APs are connected to a recent managed switch which is connected to a basic router connected to the ONT. The only DHCP service running is on the router. Its been working fine for a couple weeks.

I unplugged the router side LAN cable for a few minutes. When I plugged it back in, the computers on the wireless network went crazy with IP address conflicts. I had to reset the AP and the AEXT to resolve. The Mac I was working on was in a cycle of getting an IP address, saying there is a conflict, getting another... repeat. Anyone experience this behavior? Do I have a misbehaving AEXT? Its like the router DHCP service thinks computer A is a different computer when connected via one AP or the other. I hate to have to replace the AEXT with a dumb AP, its like an old friend :).
 

hobowankenobi

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Aug 27, 2015
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on the land line mr. smith.
So...is the Apple AE in bridge mode? Seems like maybe it's not.

Can you add a UBNT to the same SSID as a non-UBNT network? I would think not. One of the great joys of having multiple UBNT APs is that they are all the same SSID...the same network...and they have seamless handoff as devices move between them. Kinda sounds like you have the opposite of that.

As for IPs of the APs -

You could set your DHCP range to exclude a block, and then assign manual IPs to the APs, so they are never dependant on DHCP. Example:


Router: 192.168.1.1
AP #1: 192.168.1.2
AP #2: 192.168.1.3
DHCP range: 192.168.1.10 to 250


...and so on.

And technically, you can set static IP addresses (outside of the DHCP range), OR you can set DHCP with fixed addresses.

Either would work, and prevent any conflicts for the APs....which would then prevent anything from getting on the APs until they get sorted out.

Even if you did retire the AE TM box as a wifi AP and replaced with a second UBNT AP, you could still plug it in at the switch and use it a wired TM backup. That would be a lot less wifi traffic, and hypothetically faster, more reliable backups.
 
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ColdCase

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Yes the AEXT is in bridge mode.

Why would unmanaged UBNT APs vs a mix of unmanaged APs matter, as I've read that the clients decide which AP to use, right? Some clients roam more freely than others. :)

A managed network may work differently, however.
 

hobowankenobi

macrumors 65816
Aug 27, 2015
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on the land line mr. smith.
Yes, the client is the decider. Roaming and handoff get kicked around a lot as there are lots of variables.

Having the ability to fine-tune signal strengths and channels and other configurations in one place would be easier and more clear as you test. And Unfii supports Zero Handoff which may or may not be useful. Nice write up here.

I have to assume that one cannot benefit from most of the Unfi benefits in a mixed AP network...but that is an assumption on my part.

I would expect that any newish AP has a high possibility of beating anything from 2012.
 

556fmjoe

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Apr 19, 2014
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Yes the AEXT is in bridge mode.

Why would unmanaged UBNT APs vs a mix of unmanaged APs matter, as I've read that the clients decide which AP to use, right? Some clients roam more freely than others. :)

A managed network may work differently, however.
Most brands of APs have features to help with seamless transitions between them, and those features will not necessarily work together when mixing brands. I don't think it matters much for a home network. If I was buying a bunch of them for a customer, of course I'd stick to one brand. But at home I have a mix of Ubiquiti and Aruba APs with no problems.

I know you said the AE was in bridge mode, but it really sounds to me like it had a DHCP server running, since resetting it fixed your IP address conflicts. Try your network without the AE and unplug the cable again to see if you can induce it.
 
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ColdCase

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Original poster
Feb 10, 2008
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Thanks

Yeah it sounds like a second DHCP server but, when I turn off the router's DHCP server, new wireless clients cannot get an IP address. Turn it back on and the client is happy.

I'll have to wait for a quiet time this weekend to pull the plug again.

I'm thinking perhaps one AP or the other is modifying the DHCP packets differently or that there was an ARP type storm creating havoc.

For the time being I found the more centrally located UBNT is providing adequate wireless coverage so I have just turned the AEXT wireless off.

There may also be a bug in the gen 2 switch or controller. Perhaps I'll have some time this weekend to investigate, I was hoping someone here saw this behavior before.

Thanks again
 
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