IP Passthrough

IP Passthrough – H685 WRT

IP Passthrough will only work when using the H685 WRT router with a Fixed IP SIM Card.  This is becuase in order for the router to pass-through data from the Internet to your firewall, you must of course know the IP address of the router so it can be contactable.

The very first thing you should do is configure the APN settings for your Fixed IP SIM card and then once the router connects, confirm that you can remotely connect to the Public IP address of the router.  There is no point proceeding any further until you confirm your router has a Public IP address and can be contacted over the Internet.


  1. Check module support IP passthrough. Open page Network Mobile If option “IP passthrough” shown, then it is supported.
  2. Tick IP passthrough, then save & apply.
  3. Network Operation Mode, set to Bridge mode.
  4. Network>LAN>Physical Settings, check if Mobile-eth ticked.
  5. Scroll down ,tick Ignore interface, then Save & Apply.
  6. Set PC network interface to DHCP. After cell up, check PC IP address.
  7. Change PC interface to static IP, then can open router management page again.


IF YOU ARE NOT USING A FIXED IP SIM CARD WITH A PUBLIC IP ADDRESS THEN IP-PASSTHROUGH WILL NOT WORK – A standard mobile network SIM card will only provide your router with a private IP address which is NAT’ed Behind the mobile networks public IP address – so when you visit www.showmyip.co.uk this is the public IP address and your router, is on a private IP address behind this along with 250 other private IP addresses.  this is why services such as VoIP over 4G and Port forwarding/VPN Server/DYNDNS so not work with a standard mobile network SIM Card.