IP address not issued until modem reset - even if router rebooted

[realien]

Hi Guys,

I'm trying to determine if there is any way I can diagnose an issue with either my cable modem or the Asus RT 66R router. I'm running merlin wrt 3.0.0.4.378.50_0.

the modem is a Cisco DPC3000, I havent been able to access the diagnostics via 192.168.100.1

Generally the router performs well, but the on going issue I have is the router will show "disconnected" from the modem, a soft or hard reboot of the router generally does not fix the issue. I have to physically reboot the cable modem and then the router gets an IP address. It works well for a few days and then repeats, currently its been happening every 24 hours.

I've been doing a little Googling but haven't found anything conclusive on how to either diagnose the cable modem or determine if its a router or modem issue. Comcast of course says the modem checks out fine and it must be my router.

I'd appreciate any tips on how to diagnose this issue to confirm its the router or modem, or if anyone has had a similar issue and what the result was.

As a side note I had a RT AC 66U that I replaced with the 66R about a year before it gave up ever getting a new IP address so I replaced it.

Cheers
Grant

 

[darkfinger]

You mention Comcast but this is very similar to what used to happen to me on Charter cable. The issue was the way that Charter blacklist the router asking for DHCP, and I resolved it by selecting "normal" vs aggressive in WAN settings. It was extremely annoying since a reboot of the router immediately screwed things up, so making any significant changes to my router config needed me to reset the cable modem. Works great now.

Hope this helps.
Dave

 

[realien]

thanks @darkfinger - I'll give that a shot, just changed to "normal" instead of aggressive and we'll see if it behaves for a bit