Having a problem with my WiFi IP address

MagnusKnight

Odd thing happening with WiFi all of the sudden. I have been using GrapheneOS for several years now with little to no issues. I am using a Pixel 8, Android version 16, build number 2025122500. I left my house and upon my return, my phone is connecting to my home WiFi access points, however, it's getting a 192.168.1.x IP address, and that subnet does not exist as a scope anywhere in my house. I am using Ubiquit APs and I checked the Ubiquiti management console and it shows the phone is being given an IP on the correct subnet, which should work, but when I check the phone itself it does not have the IP that Ubiquiti is showing for it, but instead has this 192.168.1.x IP. Also, it's showing a gateway and DNS of 192.168.1.1 which of course is also invalid for any subnets or scopes in my house.

I have verified it's connected to the correct WiFi SSID, plus I can see it connect though my Ubiquiti, but it just seems to be assigning itself this invalid IP. I have tried disabling and re-enabling the WiFi, forcing disconnect and reconnect to the WiFi, and I have rebooted the phone, but nothing is helping.

It has never had any trouble like this before, so I have no idea why this has all of the sudden started just now when I got back home.

I then connected to my Guest network, and it did get the correct IP and gateway, but it is assigning itself an incorrect DNS server. I have no idea where it's getting this DNS server info from.

I have many network devices using wired and wireless in my house, and no other devices are having this issue, it's only this GrapeneOS phone.

de0u

MagnusKnight Restart the Ubiquiti device(s)? Try forgetting the home Wi-Fi network and then rejoining?

thmf

MagnusKnight If what de0u recommended won't improve the situation, I'd bet on a second DHCP server in the network. It may be both, a separate device or an additional DHCP scope on Ubiquiti.
You could try powering off your Ubiquiti router and try to get an IP. If you get 192.168.X.X, then you have a device with second DHCP server in your network.

de0u

thmf I like that hypothesis!

MagnusKnight

Thanks for the help with this!

The Ubiquiti isn't configured to hand out any DHCP addresses, and it doesn't have any 192.168.1.x networks defined either. The Ubiquiti APs just trunk traffic to my switch, which then gives the client an address based on which SSID it was VLAN tagged with from the Ubiquiti. The strange thing is there are no DHCP servers or subnets on my network that have a 192.168.1.x address, so I have no idea where it was getting this from.

The other odd thing is if I monitored the Ubiquiti AP and watched the when the phone connected, I would briefly see the phone have the 192.168.1.x IP address on the Ubiquiti AP interface, but then after just a second or two it would update on the Ubiquiti AP interface to show the correct IP for what the phone should be getting, but when I look at the IP settings of the phone itself, it still has the 192.168.1.x address. It's almost like when the phone first connects to WiFi, for that brief moment, it's self assigning an IP, but then it should update with the correct one when it gets a response from the DHCP server, but it's not updating and just stuck with this 192.168.1.x IP. This is why I posted in the GrapheneOS forums, in case this was like a bug or something that someone may have seen with GrapheneOS phones.

It was late when I posted this last night, so I went to bed after a short bit of troubleshooting. Before going to bed, I set the phone to a static IP, and static gateway and DNS as well, so then it worked fine and I could use it last night. I woke up this morning and changed it back to DHCP to test again and now it's working fine, no problems.

I don't know what was going on with this phone last night, but it was very odd. It's working now, so I guess I'm good now.

Thanks again for your help and suggestions! It was a really strange issue, and it looks like some kind of gremlins or something.

thmf

MagnusKnight It's almost like when the phone first connects to WiFi, for that brief moment, it's self assigning an IP,

That's possible, but then you'd get an APIPA address (169.254.0.0/16), not 192.168.1.X.

If you're interested to test a bit further, what happens if you connect your phone (or any other device for that matter) to Ubiquiti AP and manually set it's IP address to 192.168.1.X with a proper gateway from the 192.158.1.X(1?) network. Will you have access to Internet? If yes, then try to open that gateway IP in a web browser, so you'll know which device is most likely (not in 100% cases) responsible for the mess.

One more option is maybe VLAN isolation is not working properly, so you see a network segment that you really shouldn't see. For example, this is easy to get on Mikrotik devices if not careful.

Another thing that may be relevant is usually this happens when some third party "plug & play" Wi-Fi extenders are used somewhere in the house. Then sure love to plug & play their nonsense into your configuration.

MagnusKnight I don't know what was going on with this phone last night, but it was very odd.

It's not the phone. Judging by the symptoms you do have a second DHCP server with 192.168.1.X scope somewhere in your network. There's 0 chance you'd get an IP this network automatically if it's not configured somewhere.

MagnusKnight It's working now, so I guess I'm good now.

Unfortunately no, most likely you'll have this problem again someday. It's just a matter of which DHCP server will answer with an IP faster to a broadcast request from any device in your network, so that IP you'll get.

Do you use your ISP's router by chance? They usually set DHCP ranges to 192.168.1.X. If this is the case, check if DHCP server is disabled on that router. This is most likely the reason.

MagnusKnight

thmf

thmf That's possible, but then you'd get an APIPA address (169.254.0.0/16), not 192.168.1.X.

I thought about this, and I know the 169.254.0.0/16 is typical, but I was grasping at straws wondering where else this could be coming from, in case maybe this OS did something differently.

thmf Do you use your ISP's router by chance? They usually set DHCP ranges to 192.168.1.X. If this is the case, check if DHCP server is disabled on that router. This is most likely the reason.

I think you may be on to something with this. Not my ISP router, but you did just make me think about that I just ordered a Starlink internet for a backup internet connection. My Comcast goes out too often and I work from home, so I needed a backup failover. The router they sent, I plugged that into a failover WAN port in my home router, so it's possible the router was relaying DHCP offers from the Starlink router through my home router and to my internal network. I didn't finish configuring it, since the cable they sent was too short and I had to order another, but I mention this because I haven't been able to see the configuration of the router they sent, and to see if it runs a DHCP server handing out 192.168.1.0/24 addresses. I didn't think about this at first because I plugged it into the failover WAN port of the router, so it shouldn't be relaying DHCP requests or offers, but I didn't get it finished setting up, so it's possible the WAN port wasn't fully configured and it may have been acting just as a basic switch, although I didn't tell it to do that, but I suppose it's possible. Also, after all this troubleshooting I did, and since I was waiting on the cable anyway, I unplugged the Starlink router just before going to bed, so it would make sense that it wouldn't have been handing out addresses in the morning when I switched my phone back to DHCP. This is the most likely case and culprit. It could make sense that all other devices were still working too, because they had not disconnected from the WiFi in a while and were still running off of their current lease with the correct IP from DHCP, but when it was time to renew, they may have stopped working then. It also makes sense that when I got back home and tried to get a new lease, that's when it stopped working.

I think this is it. You are correct that it must be an ISP router that was doing it, and it was the Starlink that I was just setting up that I had gotten at Christmas time. It's still odd that my home router would be relaying DHCP requests and offers, but there must be something misconfigured with that failover WAN port, where it's still acting like a local LAN switchport.

Thank you for your help! I appreciate the additional thoughts and suggestions with this!

thmf

MagnusKnight This sounds very plausible. If I'm not mistaken, with Starlink you could configure it not as a router, but as a bridge so it won't have a DHCP server. But your existing router's failover WAN port will need configuration anyway. Glad you have it sorted out.