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N300 DHCP weirdness
I just installed this router on a rather complex home network. The WAN port is from a DSL router, the wireless is for a nearby house, and the LAN ports go a few places, one of which is a Ubiquiti radio link, which requires I use a static address. It appears the router blocks traffic on the LAN from devices that haven't requested a DHCP address. Adding to the reservation table doesn't seem to fix it, although the confusing results may be misleading me about reservations (and whether they need to be inside or outside of the DHCP range). As a simple test, if I connect my laptop to a LAN port (with DHCP client on) it works fine. If I connect to the LAN port with a static IP (inside or outside the DHCP range), it doesn't work. I can neither get to the internet nor talk with other devices on the LAN. I haven't tried adding the Laptop to the reservations but I have tried adding the radio device, and I can't access it with any combinations.
I can resort to turning DHCP off, but it doesn't say whether that would affect just the LAN or include the wireless which would be a problem.
After all the hand wringing, I replaced the antenna (.200 address) and everything now works. Very weird mode of failure. Sorry for all the traffic over a dead end!
13 Replies
What's your router's subnet and what static IP addresses have you tried? It's possible that you are using wrong addresses.
My router is set us as 192.168.1.1/255.255.255.0 with a DHCP pool of 49-100.
My static IP is 192.168.1.200 (which could be anything, but has to be fixed).
If I connect my laptop via DHCP, I get 192.168.1.3 and I have internet access and router, but can't see 200. If I static my laptop at 192.168.1.15, therer's no connection. If I wifi my laptop, I get 192.168.1.4 (varies), it can get to the internet and the router itself, but not to device 200.
I tried reserving the address 200, and I also tried expanding the DHCP pool to include the reserved 200.
It appears the router is following a rule that says "if they didn't ask me for an address, I'll block any traffic with them".
I'll call Netgear tomorrow, but I might just have to get a different router.
- Hmm, your laptop is getting 192.168.1.3 via DHCP while your pool is 49-100? I'm gonna guess that you have another router. Or else you are connecting to another network and don't realize it.
I've been messing with the pool, so I may have mis-spoken, but it is clearly something curious. There's another wireless router on one of the LAN ports (about 75m away in a locked building) that I've never looked at, and maybe it's plugged in wrong and being a second DCHP server? Not sure that explains the main symptom, but I'll figure that one out tomorrow. I also have another N router in my parts bin, so I can try that one after I resolve your mystery. Thanks for seeing an obvious issue!
Yes, if the other router is connected to the main network through one of its own LAN ports, and if its DHCP server it active, then it can cause major troubles. Clients that obtain IP addresses from it will send packets to it instead of the main router. Another possibility is that the second router is using the same IP address as the main router. This would confuse the heck out of devices.
If you are using the second router to provide Wi-Fi, then you should disable its DHCP server. And make sure that its IP address doesn't conflict.
- Auto MDI-X occurs during link negotiation.
https://en.m.wikipedia.org/wiki/Medium-dependent_interfaceThe NanoM9 uses a POE injector - maybe the MDI-X gets stuck? I'm just grasping at straws here - I don't have any ideas on a next stpe towards solving this problem...except uprooting my home router, which has a huge number of port forwards, etc.
After all the hand wringing, I replaced the antenna (.200 address) and everything now works. Very weird mode of failure. Sorry for all the traffic over a dead end!
