Why Can’t My LAN Devices Connect to the Internet Using Native IPv6 When the IG is used as WAN on My Router?


You observe your LAN devices are not accessing the Internet using IPv6 when the IG is in IP Passthrough mode (default, aka ‘bridge mode’) connected to your your router’s WAN (and the WAN is receiving an IPv6 passthrough address from the IG in addition to IPv4).


IPv6 address assignment and usage can vary depending on the cellular carrier and service plan. Additionally, carrier plans which do provide IPv6 addresses may not be conducive to local network routers using the connection as WAN to multiple downstream LAN devices. This is because, at least in the USA, most cellular providers do not natively support Prefix Delegation via DHCP6 and assign only a single /64 per connected device (typically via SLAAC).

Routers which support IPv6 passthrough mode and have a DHCP6 server may be successful in providing native IPv6 connectivity to LAN devices, but this can vary depending on the router. If the router lacks IPv6 passthrough and/or DHCP6, it still may be able to use NAT66 (IPv6 NAT) or a DHCPv6/RA relay/proxy as an alternative if it supports those features. Specific instructions for configuring these workarounds will vary depending on the router being used. RFC7278 provides additional information and example scenarios which may prove useful to those who wish to serve IPv6 to their LAN via a cellular WAN which provides only a /64.

Due to the variation and potential instability of cellular IPv6 workarounds when using a router, we are not able to directly support such “IPv6-to-the-LAN” scenarios currently. It is also important to note that unsolicited (inbound) IPv6 traffic is still firewalled by carriers in many cases which greatly decreases the utility of LAN devices having IPv6 connectivity.

To keep things ‘Super Simple’, most IG Carrier Profiles (APN) use an IP type of IPv4v6 which allows the IG to connect to the carrier via IPv6 if required/supported but provides an IPv4 address to the connected device, in this case, your router’s WAN. With this configuration, IPv6 terminates at the IG so users do not have to worry about IPv6 at all when connecting to a router’s WAN. When connecting the IG directly to a single client device which is not a router (ex. Laptop, Workstation, etc.) and using a carrier service plan that provides IPv6, the device may be able to access the Internet using the IG’s bridged IPv6 address natively.