DHCP problems with Motorola SurfBoard WiFi modems and DISH/DirecTV equipment

[Ichinisan]

In recent years, I've spoken with multiple people experiencing this with multiple different models of Motorola WiFi modems. If I recall, it has affected SBG941, SBG6580, and (most recently) SBG6782-AC modems.

Basically, it seems like DHCP goes absolutely haywire when Hopper/Joey/Genie devices are in-use. I suspect it's when they have an Ethernet-MoCA bridge (not really sure if these devices use standard MoCA or some proprietary implementation). In this most recent case, the modem *does* have built-in MoCA capability, but I'm fairly certain I have observed this with modem models that have no built-in MoCA features. MoCA is still enabled in the modem I'm currently looking at. I didn't change anything yet because my past experiences have led me to believe that this problem is unrelated to MoCA.

In the modem's list of DHCP clients, the satellite TV equipment keeps changing IP addresses constantly. You could refresh the list minutes or seconds later and see different IP addresses. They frequently show IP addresses with very high numbers when compared to the other DHCP clients.

I captured the list just a few minutes apart and saw the IP addresses change, but I also noticed invalid lease expiration times on the DISH Network equipment:

MAC ID       IP ADDRESS    DUR   EXPIRES                  HOST NAME
fcfc485bXXXX 192.168.0.9   3600s Thu Dec 31 12:10:27 2015 XXXXXX-s-iPad
8cdcd422XXXX 192.168.0.117 3600s Thu Dec 31 12:37:16 2015 XXXXFamily
4c82cf7bXXXX 192.168.0.2   3600s Thu Dec 31 12:35:54 2015 Hopper_br
4c82cf62XXXX 192.168.0.254 3600s Fri Dec 13 20:45:53 1901 Joey_MoCA <-- "Dec 13...1901" ?!
285767c1XXXX 192.168.0.3   3600s Fri Dec 13 20:45:53 1901 Joey_WiFi <-- "Dec 13...1901" ?!
4c82cf24XXXX 192.168.0.3   3600s Fri Dec 13 20:45:53 1901 Joey_MoCA <-- "Dec 13...1901" ?!
b0349570XXXX 192.168.0.21  3600s Thu Dec 31 12:09:59 2015 XXXXXXXXsiPhone
e0cb1d8dXXXX 192.168.0.24  3600s Thu Dec 31 12:12:42 2015 kindle-XXXXXXXXX

MAC ID       IP ADDRESS    DUR   EXPIRES                  HOST NAME
fcfc485bXXXX 192.168.0.9   3600s Thu Dec 31 12:43:44 2015 XXXXXX-s-iPad
8cdcd422XXXX 192.168.0.117 3600s Thu Dec 31 12:43:50 2015 XXXXFamily
4c82cf7bXXXX 192.168.0.2   3600s Thu Dec 31 12:35:54 2015 Hopper_br
4c82cf62XXXX 192.168.0.4   3600s Thu Dec 31 12:38:09 2015 Joey_MoCA
285767c1XXXX 192.168.0.3   3600s Thu Dec 31 12:38:10 2015 Joey_WiFi
4c82cf24XXXX 192.168.0.3   3600s Thu Dec 31 12:38:10 2015 Joey_MoCA
b0349570XXXX 192.168.0.21  3600s Thu Dec 31 12:40:00 2015 XXXXXXXXsiPhone
e0cb1d8dXXXX 192.168.0.24  3600s Thu Dec 31 12:41:32 2015 kindle-XXXXXXXXX

(I have obfuscated uniquely identifiable information)

NOTE: A Joey device's IP address changed from .254 to .4 when I refreshed the list after only a minute or so.

I'm not sure whether the Motorola modems are to blame, or the satellite TV equipment. The only cases that have come to my attention are those with Motorola modems, but perhaps that's only because those models let me log-in remotely and view the list of DHCP clients. If it's a problem with the way Motorola handles NAT/DHCP, then it has persisted across multiple models for many years.

I might suggest that this owner disable MoCA in the modem. I doubt the satellite TV equipment depends on MoCA being enabled in the modem (they usually have their own device bridging wired Ethernet to the coaxial TV lines). I still don't think disabling MoCA will help. The modem doesn't list any associated MoCA nodes/clients. If there are no other suggestions, I will just recommend that this person get a non-WiFi cable modem with a separate wireless router. Since it has 802.11ac wireless, it would be a shame to disable the WiFi in this one and enable bridge mode. I *think* some of the satellite TV equipment is using WiFi, but the DHCP table from the Motorola doesn't list interfaces.

I neglected to mention that the "DHCP Clients" table in Motorola WiFi modems will sometimes list detected devices that are *not* DHCP clients. I've seen some listed as "static" when a device is actually still clinging to an an IP address it got via DHCP before the modem was rebooted. The MoCA/coax devices usually do that because they don't sense link being lost/restored and don't renew their IP addresses automatically, which can result in conflicts.

Please let me know if you've encountered anything like this before or if you have any suggestions. Thanks!

 

[smitbret]

When it comes to DHCP I have 1 simple rule: If it is wired then it gets a DHCP reservation.

I have never had any trouble with my DirecTV or Dish Hopper/Joeys with this rule. In fact, I used to work DirecTV Advanced Technical Support and this answer solved a lot of problems for us.

 

[jardows]

Best thing I have come up with is that these satellite boxes are trying to act as DHCP servers, and use the same default subnet as the Motorola/ARRIS devices of 192.168.0.x. It is common for people to report IP address conflict errors until they contact the satellite company to reconfigure the boxes.

 

[Ichinisan]

When it comes to DHCP I have 1 simple rule: If it is wired then it gets a DHCP reservation.

I have never had any trouble with my DirecTV or Dish Hopper/Joeys with this rule. In fact, I used to work DirecTV Advanced Technical Support and this answer solved a lot of problems for us.

I tried that in the past and the DHCP reservations kept disappearing moments after I created them. Maybe that means the Motorola modem is at fault here...

On my own network at home, I do the same: 1. Wire everything possible. 2. Create DHCP reservations in the router/DHCP server.

Best thing I have come up with is that these satellite boxes are trying to act as DHCP servers, and use the same default subnet as the Motorola/ARRIS devices of 192.168.0.x. It is common for people to report IP address conflict errors until they contact the satellite company to reconfigure the boxes.

I've considered that too, but the people I speak with never have any luck with DISH/DirecTV tech support and field technicians.

I also help people with Arris WiFi modems like DG860, TG862G, TG1672G and a handful of other similar models (completely different engineering team than the one Arris acquired from Motorola Mobility / Google). Those modems also have a 192.168.0.x subnet by default and never seem to have these problems.