Skip to main content
Solved

DHCP failures: Cox Go Fast

  • November 22, 2025
  • 6 replies
  • 84 views
Eleison23
The Many
Forum|alt.badge.img+2

Greetings,

Brand new s34 and registered, activated with Cox existing service. 

The WAN syncs up, no problem. I am being careful to use only one ethernet port. According to my service plan. 

 

Now if there is no WAN, the router stays on 192.168.100.1. once the DOCSIS connection is available, the strangest thing happens: the cable modem assigns private IPv4 network from the range of 172.16.169.0/27, for example: notebook receives 172.16.169.113; gateway of 172.16.169.97; netmask is 255.255.255.224. No IPv6 assignments.

 

My Chromebook device is assigned one address, and the gateway router is listed under another address in the same network. But there is no internet access, and the despite the lights being blue, and no longer can connect to the modem on its management interface due to change in IPV4 addresses. 

 

So I don't understand where a DHCP assignment could come with private IP addresses. And there is basically nothing to configure on the S34. Certainly not a DHCP server running. It's a bridge, right? 

 

As mentioned, the DOCSIS service was working yesterday and just before I swapped out the modems from the existing panoramic Wi-Fi gateway. So I may circle back with Cox and see if we can work it out, but I'm not sure if I understand this anymore.

 

Cox Complete Care is now informed me that the WAN shows as downed, and they cannot reach the modem from head end, so a truck roll is scheduled shortly. We’ll also hope to replace this rickety old 40-year wall outlet. I may basically end up swapping bak to the Panoramic WiFi gateway in Bridge Mode here… but I pay rent on it!

Best answer by Eleison23

To troubleshoot, connect the S34 directly to a computer and power cycle it. Then, check the IP address assigned to your computer. If the S34 provides a public IP, the modem is functioning correctly. However, if it assigns a private IP, this likely indicates a provisioning issue from your Internet Service Provider. The S34 does not have a built-in DHCP server it’s a plug-and-play device—so DHCP is managed by the router.

You are correct in the fact that it was the provisioning from the ISP. 

 

However, the Private Network range was a temporary provisioning, because the DHCP lease had already been assigned to another device before I swapped routers.  The Support staff was unequipped to troubleshoot layer 3 and above and the support staff was unable to time out the DHCP before it's automatic reset.

 

It was simply a matter of powering down every device, waiting a few hours, and then powering back up after the ISP DHCP server had timed out the lease or whatever, so once I waited long enough without devices off the network the ISP was able to reassign the lease to the new the new devices that are detected. 

 

The tech also did visit and was able to detect and resolve a few layer one issues. And then finally my apartment maintenance team came to reinstall the wall outlet and cuz because it had been loose. 

 

Someday they may pull new cabling. The RG58 is from the 1980s and the text said they recommend are G6 or some such. it's more suited to the cable network applications now. But my Layer 1/2 has been fine : there's nothing wrong with DOCSIS.

 

It’s a series of tubes?

6 replies

Eleison23
The Many
Forum|alt.badge.img+2
  • Eleison23The Many
  • Author
  • The Many
  • November 22, 2025

It seems to be some sort of “Layer 3 jail” because while it appears to enjoy limited WAN access, the assigned DNS server (not the usual one) has been returning its own address for every "A" record lookup!

It’s a series of tubes?
Eleison23
The Many
Forum|alt.badge.img+2
  • Eleison23The Many
  • Author
  • The Many
  • November 22, 2025

The tech has come and gone. We had a good conversation about several things. He was only authorized to check Layer 1 and 2 connectivity, and found some old cabling and a few correctable physical problems. Apartment maintenance will be trying to bolster the wall-plate and cable jack best as they can, in 40-year-old infrastructure.

 

So we swapped out the Panoramic WiFi and I removed the ARRIS entirely, because nobody has any idea yet what the fault is, but honestly, the same issue came back with different numbers with the ISP-provided CPE, so no real progress was made yet today, except me learning about the existence of an escalation tech.

 

But it’s true that the ISP won’t touch or support third-party equipment. I was under a false impression that the extra deluxe Tech Support package would handle it when I subscribed 13 months ago. I should touch base with ARRIS but they will point back to ISP because ARRIS modem has trained up and done its job correctly; I see no faults with it, and surely it’s certified for operation with Cox anyway. These things just can’t bridge properly anymore. At my home, that is. With my current service…?

 

It’s a series of tubes?
S
Wi-Fi Warriors
Forum|alt.badge.img+42

To troubleshoot, connect the S34 directly to a computer and power cycle it. Then, check the IP address assigned to your computer. If the S34 provides a public IP, the modem is functioning correctly. However, if it assigns a private IP, this likely indicates a provisioning issue from your Internet Service Provider. The S34 does not have a built-in DHCP server it’s a plug-and-play device—so DHCP is managed by the router.

SURFboard Community Moderator Team
Eleison23
The Many
Forum|alt.badge.img+2
  • Eleison23The Many
  • Author
  • The Many
  • Answer
  • December 8, 2025

To troubleshoot, connect the S34 directly to a computer and power cycle it. Then, check the IP address assigned to your computer. If the S34 provides a public IP, the modem is functioning correctly. However, if it assigns a private IP, this likely indicates a provisioning issue from your Internet Service Provider. The S34 does not have a built-in DHCP server it’s a plug-and-play device—so DHCP is managed by the router.

You are correct in the fact that it was the provisioning from the ISP. 

 

However, the Private Network range was a temporary provisioning, because the DHCP lease had already been assigned to another device before I swapped routers.  The Support staff was unequipped to troubleshoot layer 3 and above and the support staff was unable to time out the DHCP before it's automatic reset.

 

It was simply a matter of powering down every device, waiting a few hours, and then powering back up after the ISP DHCP server had timed out the lease or whatever, so once I waited long enough without devices off the network the ISP was able to reassign the lease to the new the new devices that are detected. 

 

The tech also did visit and was able to detect and resolve a few layer one issues. And then finally my apartment maintenance team came to reinstall the wall outlet and cuz because it had been loose. 

 

Someday they may pull new cabling. The RG58 is from the 1980s and the text said they recommend are G6 or some such. it's more suited to the cable network applications now. But my Layer 1/2 has been fine : there's nothing wrong with DOCSIS.

 

It’s a series of tubes?
Eleison23
Eleison23
The Many
Forum|alt.badge.img+2
  • Eleison23The Many
  • Author
  • The Many
  • December 8, 2025

To troubleshoot, connect the S34 directly to a computer and power cycle it. Then, check the IP address assigned to your computer. If the S34 provides a public IP, the modem is functioning correctly. However, if it assigns a private IP, this likely indicates a provisioning issue from your Internet Service Provider. The S34 does not have a built-in DHCP server it’s a plug-and-play device—so DHCP is managed by the router.

POwer cycle the computer, or the S34? Or both? Usually the recommendation is 10 to 15 seconds turned off. I found that 3-hour wait was much more effective. 10 to 15 seconds will never time out the DHCP and I can power cycle it all day but the ISP would continue assigning that stop gap private network.

It’s a series of tubes?
Eleison23
The Many
Forum|alt.badge.img+2
  • Eleison23The Many
  • Author
  • The Many
  • December 8, 2025

To troubleshoot, connect the S34 directly to a computer and power cycle it. Then, check the IP address assigned to your computer. If the S34 provides a public IP, the modem is functioning correctly. However, if it assigns a private IP, this likely indicates a provisioning issue from your Internet Service Provider. The S34 does not have a built-in DHCP server it’s a plug-and-play device—so DHCP is managed by the router.

Does the S34 run a DHCPv4 client?  It does have a web management interface as a web server on an IPv4 address? That is assigned by manually?

 

The S34 does not provide or assign any IP v4/v6 addresses, public or otherwise. It would be the ISP upstream sending those DHCP leases. Over Layer 3/DOCSIS.

 

The computer connection would not be good. I want the ISP to assign the public IP to the router behind the S34. The router is the one the router is the device that receives the DHCPv4 lease assignment. If the ISP assigned the lease to the computer, it would result in further delays, as I'm not able to release that lease manually. I would necessarily wait another 3 hours for it to time out. 

 

The correct answer is that once the router was connected to this S34 connected to the DOCSIS Network and it was permitted to time out after 3 hours power down, everything was fine and the router received its the public IP v4, and IPv6 /64!

It’s a series of tubes?
Terms & ConditionsCookie settingsAccessibility statement