Rookie

is there a limit on device count to the ethernet ports on technicolor tc8715?

I wanted to have my slower ethernet devices[100] connect to 2 ports on the back of the modem and all my fast ethernet devices [1000] connect first through a cisco switch then to a single port in back of modem. However, the modem seems to only be capable of handing out a single ip address per port. So, when one slow device is operating, it gets an address and seems to work ok. If the second slow device comes up, they both struggle for a while then the 2nd becomes ok after 5-7 minutes and the first device is offline. The same is true for the fast devices. They aren't given an IP address so they can't see each other. And, it seems like only 1 is ever operational. The only thing that works well is the wifi as it has a single connection to the modem and it hands out ip addresses for anything that connects. So, is there a limitation of one device per port? I know there "shouldn't be." I am looking for a fact that confirms one way or the other.
3 REPLIES 3
Sharer

Re: is there a limit on device count to the ethernet ports on technicolor tc8715?

Glancing through my logs, it looks like the modem is grabbing at least a small subnet from 192.168.100.1 through 192.168.100.10, leaving 8 addresses to work with? See references to DHCP at the .10 address with .1 as the gateway.

An older modem I had under the TWC brand used to actually show me the ipconfig and it only allowed for a handful of private IP addresses back then. Guess it is still a thing with Spectrum as well.

If you are needing to run a larger wired home network, probably better getting your own router and having them bridge the combo unit over to run as a pass-through modem, or replace it with a stand-alone model. This way you can be in control of various aspects of your private network.
Proven Sharer

Re: is there a limit on device count to the ethernet ports on technicolor tc8715?

YES, there is a limit.  TWC previously used to restrict the number of available addresses on their rented modem/router combo gateways at 10.  Users could not modify that setting.  Then about a year before the Spectrum takeover TWC ioncreased the number of addresses to 25, still locked.  I believe that home internet user Terms & Conditions still include a LAN device limit, as well as prohibiting any servers accessible from outside the home LAN. 

 

Your device fanout plan based on speeds (100 vs Gig) makes sense.  Eight dynamic addresses should be enough to handle all your wired ethernet ports,   I suspect your gateway somehow got set into bridging mode so it is expecting to see a full router on LAN port #1 and nothing else connnected to anyother LAN port.  If that happens you won't have DHCP, NAT, DNS, or WiFi and devices connected to LAN 1 and LAN2 will fight over the single available LAN address.

 

If none of your wired Gigabit devices can see the internet or pull a valid DHCP LAN address on 192.168.1.x, then  I would suspect a bad CAT-5e patch cord between modem LAN port 1 and the Gigabit LAN switch.  Gigabit utilizes all eight leads in the cable, one broken or flipped pair can completely kill the link from the modem. 

Post back with your findings and we'll help you work through the confusion. 

Rookie

Re: is there a limit on device count to the ethernet ports on technicolor tc8715?

Thank you for your answers. I looked all over the place and could not find that information documented! If anyone else searches for "maximum number of IP addresses"; "hard limit on IP addresses"; "is there a limit to number of IP addresses"; "One IP address per ethernet port" I hope this will appear for them. I have decided to place everything inside behind personal routers and just connect to the two ports on the back of the modem.