Getting Unfamiliar IP Addresses

[MGill]

Hello everyone,

My RT-AC3200 starting having trouble last week - the SSIDs were dropping out which kept my wireless clients from connecting to wifi. Got an RMA number, its on its way to be tested/repaired.

So, pulled out my older RT-AC1900P to work as a substitute while the other router is getting fixed. During hookup I inadvertently switched the WAN and LAN cables on the router, which meant my home network was open for about 20 mins. When I came back to my wired desktop I couldn't figure out why I was getting IP addresses in a range starting with 172.x.x.x when I was expecting the standard 192.x.x.x. After 20 mins or so I figured it out, switched the wires and rebooted everything.

But now very odd behavior - especially with wireless. Its been 24 hours since my mistake and making an attempt to connect to the wifi tonight with my android phone gives me the 'connected, no internet' message. Looking deeper my phone has been given a 172.x.x.x IP address with a gateway and dns of 172.x.x.x. My router IP with my ISP is currently 174.x.x.x.

Where are these 172.x.x.x address coming from? Its happening to all my wireless clients. Ive never typed this IP into the router setup - the only odd thing that happened was my wiring mishap.

When my wife's ms surface had the same problem I was able to open the network settings, switch to static IP of 192.x.x.x and all matching IPs and the connection worked. Then I was able to switch it back to DHCP and all is good - getting IPs from the router now. But no go with my Nexus 6p or my Samsung tablet - they sit hung with these 172.x.x.x IP addresses.

Im getting paranoid with these 172 IP addresses - I dont know where they are coming from or how to get rid of them.

Ideas?

 

[Ronald Schwerer]

Hello everyone,

My RT-AC3200 starting having trouble last week - the SSIDs were dropping out which kept my wireless clients from connecting to wifi. Got an RMA number, its on its way to be tested/repaired.

So, pulled out my older RT-AC1900P to work as a substitute while the other router is getting fixed. During hookup I inadvertently switched the WAN and LAN cables on the router, which meant my home network was open for about 20 mins. When I came back to my wired desktop I couldn't figure out why I was getting IP addresses in a range starting with 172.x.x.x when I was expecting the standard 192.x.x.x. After 20 mins or so I figured it out, switched the wires and rebooted everything.

But now very odd behavior - especially with wireless. Its been 24 hours since my mistake and making an attempt to connect to the wifi tonight with my android phone gives me the 'connected, no internet' message. Looking deeper my phone has been given a 172.x.x.x IP address with a gateway and dns of 172.x.x.x. My router IP with my ISP is currently 174.x.x.x.

Where are these 172.x.x.x address coming from? Its happening to all my wireless clients. Ive never typed this IP into the router setup - the only odd thing that happened was my wiring mishap.

When my wife's ms surface had the same problem I was able to open the network settings, switch to static IP of 192.x.x.x and all matching IPs and the connection worked. Then I was able to switch it back to DHCP and all is good - getting IPs from the router now. But no go with my Nexus 6p or my Samsung tablet - they sit hung with these 172.x.x.x IP addresses.

Im getting paranoid with these 172 IP addresses - I dont know where they are coming from or how to get rid of them.

Ideas?

Very strange. I'd power off the ISP's modem. Then I'd do a factory reset on the router. Power up the modem, then redo the setup on the router. I'd also reboot all the clients that don't have the 192.x.x.x IP.

 

[MGill]

So it took me a few days but discovered the culprit. Turns out the switch of the cables did cause the issue, but I didnt realize what it was.

Finally today I have the new RMA'ed router online and everything was shut down and I started bringing things up one by one. There was in fact another DHCP server on the network giving out the 172 address - it was my Ooma Telo! Its got a setting that defaults to it being a DHCP server - not sure why it wasnt giving my trouble before but its turned off now. It appears all is good.

Just glad to know that I discovered the culprit. Thanks to Ronald for the earlier response.

Mark