Known Issues:

  1. SIP ALG is enabled by default.
  2. DNS relay/proxying can cause the above issue as well however by default DNS relay is disabled, but if it was turned on it must be disabled.
  3. We need more information on this router to find out if the other basic router requirements can be applied to this router.
    • Please contact Intermedia Voice Technical Support so we can better document other necessary changes that need to be made to this router.
  4. TimeWarner Arris TG1672 v.1 is vulnerable to PixieDust attack and can be locked out immediately by TimeWarner if under attack.


  1. Log into the router
  2. Go to Firewall > ALG
    • Uncheck SIP ALG
    • Check Allow ICMP Ping
  3. The remaining steps are only needed if you have or plan to purchase Polycom phones:
    • Go to LAN Setup > Check the DNS Override box enter:
      • Primary DNS Server:
      • Secondary DNS Server:
    • Enable DNS Relay: Uncheck
  4. Reboot all phones, computers, and other devices on the network to clear their DNS cache & reconnect.
    • You may need to manually flush the DNS cache on your Windows computers using the command below from Command Prompt:
      • ipconfig /flushdnsYou will need to save changes andReboot all phones, computers, and other devices on the network to clear their DNS cache & reconnect.

Permenant Resolution:

If any of the above options are not present then purchase a recommended router:

  • Purchase a Recommended Router if you do not have one already.
    • Intermedia cannot setup the new router for you, but your IT or the manufacturer of your new router can help you. 
  • Call your Cable ISP to bridge your internet gateway to your new router.
    • Note: It is at the discretion of the ISP, whether or not they will allow the modem to be bridged. If they choose to deny the request, then the above resolution will apply.

Additional Resources:

  1. Recommended Routers.
  2. Recommended Switches.
  3. Recommended LAN Configurations.
  4. Network Ports and Protocols for HPBX phones.