Unifi Network - USG loses power - no internal WIFI as well as internet

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davidcole

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#305724 31-May-2023 09:03

So some background. I have two UPS. One with my main computer and the USG.

The other UPS has a machine with the unifi controller, my main network switch and a switch for my APs.

I'm picking the UPS with the main computer/usg has old batteries and doesn't stay up anymore with a power drop.

So when I woke up this morning, lenovo smart clock was complaining no wifi. My phone also. Only when I restored power to the USG did it all connect again.

My question is why, if the USG is down do I lose wifi? I thought with the unifi controller still powered, switch still powered and APs still powered that I should still have internal wifi, just no internet.

And is there a way (short of chucking out the unifi system) of having the wifi stay up.

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davidcole

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#3082644 31-May-2023 09:19

So looks like because the unifi is serving DHCP, and I had a really stupidly short lease time (1 hour) that could be a huge part of the problem. Have extended lease time to 48 hours.

I might see how that goes when I drop power on it (which I'll do as part of replacing the batteries).

Jiriteach

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#3082667 31-May-2023 09:53

Yup - the USG will be providing DHCP. If the lease is long enough - it should be OK since the controller is still up. Then again the controller could go as well and the AP's should still be up. Or set static IP's for your AP's.

-- opinions expressed by me are solely my own. ie - personal

allio

887 posts

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#3082675 31-May-2023 10:31

My wifi drops when my internet is down though my only Unifi equipment is APs and the controller. Very annoying. I looked into it a while ago and it seemed to be intentional behaviour - i.e. Ubiquiti think it's better for the whole wifi network to disappear if there's no internet so you don't unknowingly connect to a SSID with no connectivity. I disagree...

fe31nz

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#3083063 1-Jun-2023 00:30

allio:

My wifi drops when my internet is down though my only Unifi equipment is APs and the controller. Very annoying. I looked into it a while ago and it seemed to be intentional behaviour - i.e. Ubiquiti think it's better for the whole wifi network to disappear if there's no internet so you don't unknowingly connect to a SSID with no connectivity. I disagree...

I have a FlexHD AP and the controller software running on a PC and I do not see this at all. I can not see anyone actually making the decision to have the WiFi drop deliberately when there is no Internet access - it is just so blatantly silly. There are heaps of things that use a network and do not need any Internet connection, starting with lots of IoT devices, use of file servers on the local network, MythTV frontends connecting to the backend PC, ... So if the Internet connection being down is preventing your WiFi from working, there is something very strange going on that is making that happen. All the documentation I have seen for the UniFi controller says that if it is offline, the APs wills still keep working just fine, and that is my experience. The APs do not poll for Internet presence, so they do not even know if it is gone. One thing that would cause a problem like that would be if you were using a DNS server for local DNS names that is somewhere out on the Internet, but that would be a very unusual configuration.

davidcole

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#3083070 1-Jun-2023 06:40

Ive tried extending my dhcp lease time (at the USG). But when I took the power out last evening to replace batteries in the ups. I noticed the same behaviour.

I think I’d set an uplink monitor to my main 24 port switch. There was a check to ping.ubnt.com that I hadn’t changed to an internal ip.

Unsure what else I can do.

BarTender

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#3083072 1-Jun-2023 07:04

Build a second internet connection with failover if your primary goes down? I think you will need a redundant DHCP and DNS service to resolve all your internal services and the DNS resolver will need to support working when the upstream is offline. Dnsmasq supports it with a flag.