Visitor
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4 Messages
Motorola MB8611 and Firewalla Gold Router. DHCP not work on Xfinity?
I've used NetGear and LinkSys routers for seven years on ComCast Xfinity. Acquired a Firewalla Gold router/firewall to tackle a problem where I have to cycle power on everything weekly to keep Siri talking and the doorbell working.
I can't figure out why your network can't accept DHCP from a storied company like Firewalla connected to a Motorola modem (that has no router).
Fearing a hardware issue, I put the LinkSys modem back, it came right up. Took screenshots of the network / DNS settings.
Swapped in the Firewalla and DISABLED DHCP, put in a static IP, netmask, gateway, both DNS servers.
Worked brilliantly until 8:30AM the next morning. Not supposed to switch out of DHCP mode?
I am able to use your website to reboot the modem all day..
Connecting to AWS? Alas, my Xfinity service is apparently in Zombie mode. It's alive but nothing works.
So, any router works as long as it wasn't designed by Ex-CISCO engineers?
Robert [Edited: Personal information]
Accepted Solution
user_303500
Visitor
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4 Messages
2 years ago
Follow up, I have discovered that Comcast/Xfinity saves the MAC Address of the router/firewall. If the MAC address changes, DHCP refuses to connect. If you switch to static, everything is blocked by 8:30AM the next day.
After several days, Firewalla support suggested that I use a common SOHO function: MAC Address spoofing. Fortunately, the old LinkSys router still worked. Plug that back in, log into the config page, copy its MAC address.
Plug the new router in, copy the MAC address. Restart everything. Its been solid ever since.
Not sure why no one talks about this problem very much. Definitely cost me several days of poking at it.
Since the new router is a clone of the old one, I'm a bit afraid to drop it off at the nearest charity.
Fundamental problem with Xfinity: when nothing works. Go to their website/app.
Send a reset signal to the modem. Resets the modem but didn't work on the problem I was struggling with.
Shouldn't XFinity also trigger a renewal of the DHCP lease that, ideally, would grab the MAC address of the new router (suspect this is needed for NAT to work) during modem reset?
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user_079458
Visitor
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21 Messages
2 years ago
You are not the only one having that problem despite the silence from Xfinity's side. I had a problem with not getting ipv6 address via dhcp6. It didn't work with Xfinity's own modem with bridge mode enabled and it didn't work with my own MB8611. It only worked when with the Xfinity's modem with bridge mode disabled.
ipv4 was working fine.
Finally figured out that by changing the mac address to the one that I got from an usb ethernet adapter made everything work. I'm still waiting for some explanation from Xfinity on this.
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user_303500
Visitor
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4 Messages
2 years ago
oof. That's annoying. You would think XFinity's modem/router should be in bridge mode.
kudos on the usb ethernet adaptor for a new mac address idea.
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user_303500
Visitor
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4 Messages
2 years ago
Seems that being able to spoof a MAC address would be bad. Guess not.
Oh well.
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