DHCP server stopped working

[Joacim]

I realized that my "Home Hub 4000" Fiber-modem / WiFi Router suddenly stopped answering DHCP Discovery Request sent from some of my computers. It started with one, then the day after it was 2 more. It's not related to access type as ethernet and wifi connections had the same issue. Static configuration of IP address worked fine. 

The issue was resolved by restarting the "Home Hub 4000" Fiber-modem / WiFi Router. DHCP is now working for all connected ethernet and wifi devices in my LAN.

Working with network equipment myself I believe this is a bug in the "Home Hub 4000" Fiber-modem / WiFi Router which should be addressed. 

[BellPatricia]

Hey @Joacim. Thanks very much for sharing this with the Community.

Feel free to post if you discover any other hiccups.

- Patricia 

[ZaneP · Accepted solution]

Hi @Joacim 

Here's a thought.

Could you take a moment and have a look in the HH4000 log?  Say on or around the date you first noticed the DHCP server issue. It would be interesting to see how the event(s) was described, and could provide some useful information for Bell Tech Support.

On the dashboard, System Logs are in Advanced Tools and Settings. You can use the custom filter to see logged messages for just the DHCP server and DHCP client.

Cheers,

ZaneP

[Joacim]

It happened again. This time multiple devices got disconnected. My Home Hub 4000 Fiber-modem / WiFi Router suddenly stopped answering DHCP Discovery Request. Not all devices are impacted and static IP configuration is working fine. 

I checked the system log and there is nothing that stands out. I can email it to you. I don't want to add it to this chat.

The problem was resolved yet again by rebooting the router.

I don't think this is acceptable as I got thrown out from a TEAMS conference bridge for work. I also remotely log in to different sensitive customer equipment in my work and being disconnected can cause possible harm.  

[Joacim]

When I filter on DHCP in the system log I only see the DHCP server restarting during reboot (date = 12/31/2012) of the router, see below.

Date/Time	Level	Module	Message
12/31/2012 19:00	INF	DHCPS	The LAN DHCP Server is active
12/31/2012 19:00	INF	DHCPS	The LAN DHCP Server is active
12/31/2012 19:00	WRN	DHCP	The LAN DHCP Server is inactive
12/31/2012 19:00	INF	DHCPS	The LAN DHCP Server is active
12/31/2012 19:00	INF	DHCPS	The LAN DHCP Server is active
12/31/2012 19:00	WRN	DHCPS	The LAN DHCP Server is inactive
12/31/2012 19:00	INF	DHCPS	The LAN DHCP Server is active
12/31/2012 19:00	INF	DHCPS	The LAN DHCP Server is active
12/31/2012 19:00	WRN	DHCPS	The LAN DHCP Server is inactive

[ZaneP]

Hi  @Joacim 

I'm really not sure what's going on with your HH4000. I've used the 4000 for several months, without having any DHCP problems.

I'm surprised that there's no logging of these DHCP events (but no need to send me the log). 

I make no claims of expertise in DHCP, but here are some thoughts.

We assume that all client-side devices are sending the discover message, so why the server isn't answering with an offer message is uncertain. If there's a firmware problem re the DHCP server I assume it would widespread among the HH4Ks and Bell would know about it. But your issue seems to be an intermittent failure, cured by a reboot.

It's also unclear why a connected device is suddenly being disconnected, once it has an assigned IP addresses. The lease isn't being renewed?

There are challenges in capturing/auditing errors in these consumer-focused gateway modems. There's not enough granularity and customization. You could try running Wireshark to look at traffic re the DHCP requests. 

IMO, you really should be having a conversation with Bell Tech Support, and escalating the issue if there's no clear solution. Perhaps a replacement HH4K would be useful.

Meantime, a possible brute-force workaround: give all the computers a static IP address (via the dashboard/My Devices/Settings/IP type = Reserved).

Or you could extend the leases of the devices that have a dynamic address.

Given that your scenario involves mission-critical work, you may want to consider connecting a higher-end 3rd party router to the HH4K and use its DHCP server and other functions (like WiFi). The HH4K would run in "modem-only" mode.

Hope this helps a little.

[BellPatricia]

Hey @Joacim & @ZaneP. Great conversation. Thanks for sharing all of this information!

We just wanted to jump in to get a bit more info. Which device(s) disconnect, and can you provide us with timestamps?

- Patricia

[SGSCott]

Hi All.  I found this googling.  I have the exact same issue.  I've been a customer for 3 weeks and the issue just began.  First with the ethernet wired connected Windows pc.  A restart of the router sometimes fixes it, not always.  Wifi connectcitons seem fine (chromebook, android, Ios), but a windows laptop via wifi has the issue also.  

Any suggestions ?

[ZaneP · Accepted solution]

Hi @SGSCott 

I suggest you do a factory reset of the modem, rather than another restart/reboot. You'll need your login credentials ready after the reset.

If that doesn't do anything to fix this issue, you should call Bell tech support and describe the problem. 1-844-310-7873.

You may be offered a replacement modem, which I would accept if I were you. If the issue continues even with a new modem, then you'll need more trouble-shooting help.

Keep us posted.

Cheers,

ZaneP

I don't work for Bell, just a customer

[Joacim]

Hello,

My issue went away by itself. Possible there was a firmware upgrade that sorted it out. By the way as earlier suggested you can try static configuration of IP to test if the issue is related DHCP or not.

[SGSCott]

Hi @ZaneP .  Thanks for the responses.   I'll keep you posted should it be helpfull too for anyone else.   I did a factory reset, just today, will see how it goes. All was fine immeditely after, interestinly including, albeit subjective,  better speedtest results (my own, not the router's speed test feature).  Bell confirmed i'm on current firmware (1.16.5).  They are sending me a replacement router.    Will update again if there is  anything of interest. 

[SGSCott]

Hi .  Update:  Factory reset 2 weeks ago and have not had any issues since (2 weeks now) .  However, since I received a replacement router,   today I swapped it in.   Just too to note, this replacement router is firmware  1.19.5.1 

[SGSCott]

Update:  Well i'm back to square one.  Same issue exactly .  Even with the new router, which was fine for 2 days.  That ,  all  chromebook, android, ios devices are totally fine, no issues re wifi.   My two windows (11) machines are the issue.. have no internet access.  ..  One of these two windows machines is ethernet wired directly to the router (3 feet away), the other windows device is via wifi .   e.g. Windows says "cant' reach DHCP server" , and that's true since I can see on the windows side there is no IP assignment , dns servers, etc.   I'm sure even if i put the the arduous effort to navigate the support channels , I suspect they will just assume that the issue is rare and/or isolated to me, thus it's my issue , not a bell issue.  However  my same devices were rock solid with Cogeco ...for the past several years. 

Also fwiw,  for my situation I simply can not sustain this instability/unreliability.  It's unfortunate but have no choice but to cancel the service.  For comparison, with  Cogeco i had zero tech issues for the past several years....and of course now regretting the move.   THanks for the help along the way though.

[SGSCott]

Hi All.  Another update.  After pondering what is unique about my setup and why every one of  my windows machines are having issues with a dhcp dialog with the router (they never do get any ip assigned) , i had the thought to disconnect (unpluged) the wifi extender that bell installed with my new internet serivce.  The wifi extender is a part of the smart home offer (i have a security camera that connects to the extender ssid (e.g. "Bell031_EXT" which in turn is connected to my main wifi ssid.  "Bell031" ).   The extener is modelTL-WA850RE.   Oddly, even though it is fully unplugged (power), in the gigahub mgmt portal (192.168.2.1), it is still showing as a connected wifi device. Before i disconnected it, it always showed connected, but unlike other devices the connected wifi icon was always grey'd out ....and still does even thought it's fully unplugged  This is why i had had the thought to pull the extender.   The good news is that for the first time, my various windows machines all connected  fine.    I can't see the logic in this, other than somehow the extender seemed to have some influence over the dhcp protocall ...and impeding windows trying to lease an ip.   Let me know if any of this is fodder for feedback or comments.   Many thanks

[SGSCott]

Oh - i should add too... i also pull the plug on another alarm.com device that bell installed..the "Smart Gateway" (ADC-SG130Z)...  from what I can tell, it has no practial purpose for me anyway.