[Asus RT-AC-68U] Strange DHCP replies

[AjayGhariwala]

Hi there,

My N66u died a couple of months ago and i decided to take the plunge on the 68u. Experienced a fair a amount of disconnects and instability on it and switched over the Merlin's builds. Currently on the 3.0.0.4.374.40_alpha4 which i just loaded. Link speeds seem much better now.

However, I've been experiencing strange DHCP replies on my devices. My network was initially on 198.168.0.XX. I kept getting DHCP replies of 192.168.11.XX on my clients ( 2 x Andriod's, 2 x Macs, 1xapple TV & 1 Samsung TV). I worked around by hardcoding my ips but it really annoying on my androids where i have to keep disconnecting and reconnecting to get a proper addressable IP. I have since changed my addresses to 192.168.1.XX but to no avail. I thought it my be related to my ssynology ds-414 .. but even when its off, Im still getting these strange values. Contacted ASUS but I'm not getting anywhere with them, which is why I'm posting here.

Here is a example of what Im seeing in my log..

Apr 5 16:13:01 dnsmasq-dhcp[5995]: DHCPDISCOVER(br0) 78:52:1a:9b:d8:0d
Apr 5 16:13:01 dnsmasq-dhcp[5995]: DHCPOFFER(br0) 192.168.1.151 78:52:1a:9b:d8:0d
Apr 5 16:13:01 dnsmasq-dhcp[5995]: DHCPREQUEST(br0) 192.168.11.6 78:52:1a:9b:d8:0d
Apr 5 16:13:01 dnsmasq-dhcp[5995]: DHCPNAK(br0) 192.168.11.6 78:52:1a:9b:d8:0d wrong server-ID
Apr 5 16:13:04 dnsmasq-dhcp[5995]: DHCPDISCOVER(br0) 14:10:9f:f1:ca:3c
Apr 5 16:13:04 dnsmasq-dhcp[5995]: DHCPOFFER(br0) 192.168.1.208 14:10:9f:f1:ca:3c
Apr 5 16:13:04 dnsmasq-dhcp[5995]: DHCPREQUEST(br0) 192.168.11.7 14:10:9f:f1:ca:3c
Apr 5 16:13:04 dnsmasq-dhcp[5995]: DHCPNAK(br0) 192.168.11.7 14:10:9f:f1:ca:3c wrong server-ID
Apr 5 16:13:04 dnsmasq-dhcp[5995]: DHCPREQUEST(br0) 192.168.11.7 14:10:9f:f1:ca:3c
Apr 5 16:13:04 dnsmasq-dhcp[5995]: DHCPNAK(br0) 192.168.11.7 14:10:9f:f1:ca:3c wrong server-ID
Apr 5 16:13:04 dnsmasq-dhcp[5995]: DHCPREQUEST(br0) 192.168.11.7 14:10:9f:f1:ca:3c
Apr 5 16:13:04 dnsmasq-dhcp[5995]: DHCPNAK(br0) 192.168.11.7 14:10:9f:f1:ca:3c wrong server-ID
Apr 5 16:13:06 dnsmasq-dhcp[5995]: DHCPREQUEST(br0) 192.168.11.7 14:10:9f:f1:ca:3c
Apr 5 16:13:06 dnsmasq-dhcp[5995]: DHCPNAK(br0) 192.168.11.7 14:10:9f:f1:ca:3c wrong network
Apr 5 16:13:06 dnsmasq-dhcp[5995]: DHCPDISCOVER(br0) 14:10:9f:f1:ca:3c
Apr 5 16:13:06 dnsmasq-dhcp[5995]: DHCPOFFER(br0) 192.168.1.208 14:10:9f:f1:ca:3c
Apr 5 16:13:07 dnsmasq-dhcp[5995]: DHCPREQUEST(br0) 192.168.1.208 14:10:9f:f1:ca:3c
Apr 5 16:13:07 dnsmasq-dhcp[5995]: DHCPACK(br0) 192.168.1.208 14:10:9f:f1:ca:3c HotPro

Anyone have any clues to whats happening?

 

[RMerlin]

Either you have a client with a static IP in the wrong subnet, or you have a client with a lease obtained from a different router, in a different subnet, and it's asking your DHCP server if it can use that IP (which gets appropriately turned down by the router).

 

[AjayGhariwala]

Either you have a client with a static IP in the wrong subnet, or you have a client with a lease obtained from a different router, in a different subnet, and it's asking your DHCP server if it can use that IP (which gets appropriately turned down by the router).

Thanks! Don't have any other routers and my I'm not running a DHCP service anywhere else. Since loaded your latest beta release, some 8 hours ago, and i did a hard reboot, I haven't notice any strange assignments. Fingers crossed it stays this way. Once again thanks and really appreciate your work!

 

[RMerlin]

Thanks! Don't have any other routers and my I'm not running a DHCP service anywhere else. Since loaded your latest beta release, some 8 hours ago, and i did a hard reboot, I haven't notice any strange assignments. Fingers crossed it stays this way. Once again thanks and really appreciate your work!

I'm talking about a client, not another server. This is quite common if you have a phone or a tablet that was connected to someone else's wifi - when you get home, it will try to keep the DHCP lease it previously obtained at the other location, and will be turned down by your router's DHCP server.

 

[AjayGhariwala]

Figured it out. It was a rouge DHCP server. I plugged my cable modem (which is in use for Voice services but not internet) into one my switches by mistake. Its off hidden in a corner and only after looking at it that an ethernet cable was plugged in. Gosh.. User error!

Thanks for the assist none the less!

Cheers!