Router giving out IP's outside of DHCP range?

[Theguywhobea]

Hi All, I have a decently new TP-Link router that has been working fine, however I have recently started noticing on my desktop, my phone, and my girlfriends phone, that I will occasionally not be able to connect. The strange thing is when I check what my device is doing when it won't connect is it's getting an IP address of 192.168.230.XX where as my normal DHCP range is 192.168.0.100-249. I am typically able to resolve the issue on my desktop by unplugging the ethernet cable a few times until it connects again. On my phone over Wifi it just seems to start working again after a certain amount of time and nothing I do resolves it.

 

Anyone know why my router would be doing this? At least from what my phone is saying it claims to be connected to the router, but it can't connect to the internet. When this happens on my desktop I can't ping the router unless I go and manually set my IP to something on the 192.168.0.xx subnet (which makes sense)

[Falcon1986]

23 minutes ago, Theguywhobea said:

Anyone know why my router would be doing this?

What device is upstream from the TP-Link router? Please reference exact make/model.

[Theguywhobea]

8 minutes ago, Falcon1986 said:

What device is upstream from the TP-Link router? Please reference exact make/model.

The WAN side of the router is connected to my Fios gateway in my basement/garage. This is not the router that they try to sell you, it's just outside the fiber termination box, so I'm not 100% sure but I believe it's part of the media conversion from fiber to copper/ethernet.

 

My TP-Link router is an AC1750

[Theguywhobea]

Here's an update. It has to be some kind of DHCP issue. I tried restarting my phone several times, restarting the router, forgetting the network on my phone, using device MAC or randomized MAC. None of this changed anything. Then I forgot the network settings, and used a static IP when connecting and it can connect to the internet fine that way. How do I even solve DHCP issue like this? The router doesn't seem to think it's doing anything wrong.

[Slayerking92]

When you get a 192.168.230.x IP address, open a command window and type IPCONFIG /ALL and it will tell you the IP address of the DHCP server that was used. It could be some other device plugged into your network.

[Needfuldoer]

Sounds like you've got a rogue DHCP server somewhere on your network.

[Falcon1986]

19 hours ago, Theguywhobea said:

The WAN side of the router is connected to my Fios gateway in my basement/garage. This is not the router that they try to sell you, it's just outside the fiber termination box, so I'm not 100% sure but I believe it's part of the media conversion from fiber to copper/ethernet.

Is this FiOS gateway also running a DHCP server? Most fiber gateways are combo devices, which means that they also have a router built in. If it's not set up to run in bridge or passthrough mode, it will still try to manage LAN IPs, albeit from a different subnet.

 

Go to 192.168.230.1 in your browser to see what it brings up.

[Alex Atkin UK]

8 hours ago, Falcon1986 said:

Is this FiOS gateway also running a DHCP server? Most fiber gateways are combo devices, which means that they also have a router built in. If it's not set up to run in bridge or passthrough mode, it will still try to manage LAN IPs, albeit from a different subnet.

 

Go to 192.168.230.1 in your browser to see what it brings up.

Although this should only be a problem if the WiFi is still active on the gateway and the phone is switching to it.  Plus the Internet should still work when that happens unless its some sort of broken bridge mode where its no longer performing NAT but still giving out DHCP, so its a bit odd all around.

[Donut417]

14 hours ago, Falcon1986 said:

Is this FiOS gateway also running a DHCP server?

Based on what the OP states, the fact this isnt the router they sell you, I think the OP has just the standard ONT. Because Verizon last I checked doesnt use a gateway. They have a standard ONT and have their own router that they will sell you. 

[Theguywhobea]

On 8/24/2022 at 7:26 AM, Donut417 said:

Based on what the OP states, the fact this isnt the router they sell you, I think the OP has just the standard ONT. Because Verizon last I checked doesnt use a gateway. They have a standard ONT and have their own router that they will sell you. 

Yeah correct, it's just the ONT in my basement/garage. I don't rent any equipment from Verizon. Seems like maybe their could be some rouge DHCP device but I don't know, wouldn't I be double NAT'ed or something if that was the case?

[Alex Atkin UK]

Just now, Theguywhobea said:

Yeah correct, it's just the ONT in my basement/garage. I don't rent any equipment from Verizon. Seems like maybe their could be some rouge DHCP device but I don't know, wouldn't I be double NAT'ed or something if that was the case?

No, a rogue DHCP just means whichever responds first will assign the IP to the client and so whenever the DHCP lease expires you have no idea which one will assign to the new IP.

[wseaton]

I'm not familiar with this router, but I've seen an increasing number that will assign different DHCP ranges for wifi vs wired. Often the tables are buried and not very easy to tell apart.

 

Otherwise it's a rogue DHCP server.

[Theguywhobea]

I think the rouge DHCP server just gained some more merit. My desktop was doing this again today so I decided to do a network audit. Ran AngryIP and found a device on my network that had a web server running that I couldn't access. It had no name in the router table and when I looked up the MAC it was some Shenzen Trolink company. I went through a mental list of all my network devices and couldn't figure out what that could be so I blocked it from accessing the network at all. After doing that I ran a /release /renew on my desktop and was able to grab the correct IP. I think that maybe fixed it?

[Falcon1986]

16 hours ago, Theguywhobea said:

Shenzen Trolink

Do you have any IoT devices, like smart bulbs or plugs?

 

16 hours ago, Theguywhobea said:

so I blocked it from accessing the network at all.

Excellent!

[Theguywhobea]

On 8/27/2022 at 9:30 AM, Falcon1986 said:

Do you have any IoT devices, like smart bulbs or plugs?

 

Excellent!

The only one I have is a garage door opener, no smart bulbs or plugs anywhere else. I saw my garage door opener on my list of connected devices so I know it wasn't that. Kind of creepy, and my router did identify it as a camera which is even creepier. Haven't had the issue since blocking this device from my network.

[Lurick]

You don't have WPS enabled in your router by chance do you?

[Theguywhobea]

3 minutes ago, Lurick said:

You don't have WPS enabled in your router by chance do you?

No I don't believe I do. I don't think I've ever used that on any network.