[rem2500]

Hi DD-WRT Experts!

I am coming back to DD-WRT after about 10 years away. I purchased a Netgear R7000 and successfully flashed it with DD-WRT v3.0-r31520M kongac (03/01/17). I have an Arris SBG6400 cable modem which I have been using for several months before getting the R7000. Once I flashed the R7000 I put the Arris in bridge mode and restarted it and the R7000. I also cloned the MAC address for the Arris on the R7000 since I have Comcast as my ISP and I know that they require the MAC to be registered.

I have restared the devices in various orders and numerour times over the past 2-3 hours and the R7000 has never gotten a WAN connection from Comcast. When I reset the Arris to factory default it comes up and works just fine and pulls all the necessary WAN information.

Is there anything else I can try?

Thanks
REM2500

[aniel]

try WAN Connection Type to static/apply then change back to automatic

[jmmilner]

I've had similar issues with other DDWRT builds - currently I'm on DD-WRT v3.0-r30082 std (07/01/16) using a WNDR3700v4 and an Arris SB6183.

I've yet to find a synchronizing sequence, in the FSM sense, that will repeatedly bring up my modem and router after a power outage (brief ones are bridged by a UPS) or if the IPv4 address fails to renew and expires. Switching to static and back to automatic will sometimes work but in my experience is far from certain.

Enabling IPV6 does allow me to reach the XFINITY program guide but is the kiss of death for my IPv4 address. I've had the best luck with printing all my settings to PDF files using the build-in PDF in Chrome, wiping the router to defaults,and then manually reentering all my settings and IP reservations. As long as I don't enable IPv6 the IPv4 address seems to renew every 2 days (lease is 4 days) and has done so for 2 weeks.

I've gone back and forth with Comcast on this to no avail but they don't have a solution and I don't have an alternate ISP available.

Are you using just IPv4 or also IPv6?

[aniel]

i use to have a problem where it will drop connection after 30 minutes or so but it ended up being that the gateway needed to be on bridge mode, i dont think this is the case but yes my Asus RT-AC68U running DD-WRT v3.0-r31205M kongac (02/03/17) had problem getting ip from modem until i discovered "try WAN Connection Type to static/apply then change back to automatic" im still testing this solution but i think its working all good, at the end of the day i think is a bug on ddwrt, hopefully they will fix it.

[rem2500]

Hey guys,

Thanks for the replies!

I tried changing the WAN connection type to static and then back to DHCP with no luck.

I have been using just IPV4 but I did notice that my Arris Cable Modem / Router pulls both IPV4 and IPV6 addresses. I did try early on to use IPV6 as well with no luck but maybe I need to try that again.

Also, I tried to get the values from my Arris to use on my DD-WRT build but it does not show a gateway for IPV4 so I am a little lost there...

Thanks
REM2500

[jmmilner]

I'm currently under 2 hours from my 48 hour IPv4 lease expiring. By the standards it should have started trying to renew when the lease was half over but obviously that didn't happen. I think I'll wait this time and confirm that the supposed Comcast dual stack (v4/v6) doesn't play nicely with DDWRT - consistent with my past observations.

That the trick of changing to static, apply, and then return to DHCP fails isn't a surprise - see it all the time. Even when it "works" I'm not sure if it is really the reason or just a coincidence.

My fallback plan is as stated in my prior post, wipe the router to defaults and reapply everything via the GUI. If you've played with IPv6 and not subsequently tried the the wipe & reapply approach, I'd suggest you try it and document your results. I'd like to know if anything I'm doing is actually cause and effect or just chance!

I'm guessing IPv6 in DDWRT just isn't playing nicely with Comcast. Being a U.S. company, Comcast is likely playing games with the strict implementation of the standard to allow them to harvest more customer-specific data that they can mine for their own business or sell to third parties. DDWRT, being primarily developed in Germany, likely sees more ISPs who follow the standard since the EU has privacy laws about customer-specific data tracking.

For now I'll just go back to straight IPv4 and do without Comcast's program guide. I'm about ready to drop cable TV anyway so it isn't a big deal to me.

[jmmilner]

So I let my IP lease expire. About 3 hours later Comcast released the IP address and all my networking when south. Unplugged the modem, router, powered off the PC and waited overnight. Powered up the modem, waited 15 minutes, powered up the router, waited 15 minutes, powered up the PC - no internet.

Called Comcast. Internet tech support call transfer when to "please try your call again". Called to disconnect service. Sent me to tier 1 support, who couldn't help, sent me to tier 2 support who tried a bit harder. According to him, don't bother with IPv6 on your local network, it just doesn't work - stick with IPv4 for your LAN. Comcast modems will tunnel IPv4 over the IPv6 connection that they establish with the CMTS. As to why expiring of that IPv6 address always hoses my network connect, no clue. Sent me to tier 3 who turned out to be a gatekeeper who repeated the same power cycle drill. Finally passed me to a tier 3 person who was really just a business wireless gateway person who couldn't grasp that my cable modem wasn't 10.1.10.1 - SB6183 anybody? They wrote a ticket for somebody to call me back.

Finally I stumbled on what appears to work. It isn't easy but if you can get a tech who will just do a hard reset (not the fake reset the automated system claims to send) of the cable modem while your router is powered off, at least the SB6183 forgets the CPE MAC and once the router is powered up it issues a valid IPv4 address to my router.

The message you want to see in your modem event log is:

Day Mon NN HH:MM:SS YYYY Critical (3) Resetting the cable modem due to docsDevResetNow

Note there is no log entry for the fake reset the automated system "sends".

Time will tell if subsequent extensions of the lease are honored. I expect once the underlying IPv6 lease finally expires (roughly every 30 days per tier 2), I'll have to repeat this silly dance.

I'd prefer to keep Comcast as my prior experience with U-Verse is even worse but having to play tricks with their system to implement a simple basic IP address renewal seems inane.

Somewhere about call 5 of the 9 it took to get this done I did release Comcast of the burden of providing my cable TV which should save me a few bucks.

[rem2500]

I found a solution to my problem here: http://forums.xfinity.com/t5/Your-Home-Network/Xfinity-Cisco-DPC3941T-Bridge-Mode-Issues/m-p/2632838#M32515

Basically here are the steps that fixed it:

1) Press and hold reset button on back of gateway for 30 seconds, this will reset the gateway back to the factory defaults..

2) Connect a computer to ethernet port #2 on the back of the gateway.

3) After the gateway boots, verify computer has connectivity, connect to gateway @ 10.0.0.1

4) Change the gateway's login password, disable both private wifi networks

5)(I didn't have to do anything here but leaving for completeness) set ipv4 and ipv6 firewall to custom mode and select option disable/none.

6) Set Gateway > At a Glance > Bridge Mode to Enable. When you see the timer screen pop up, you can disconnect the computer from the gateway as it is rebooting. the reboot can take 3 - 5 minutes.

7) Connect your router to the gateway ethernet port #1, on the router make sure that the WAN / Internet link is set to disabled or off.

Once the gateway completes it's boot cycle, enable the Internet WAN on the router. The router should now have the IP address issued by Comcast.


Thanks for all the replies!
REM2500

[aniel]

Glad you were able to fix it