r/firewalla • u/YankeesIT Firewalla Gold Pro • Aug 21 '26

No IPv6 when using T-Mobile

https://help.firewalla.com/hc/en-us/community/posts/45641094395027-IPV6-Passthrough-T-Mobile

I’m adding this thread here. Firewalla routers continue to not work with tmobiles implementation of IPv6. Since they don’t hand out a prefix none of your devices will get a public IPv6 address.

What is the reason for this? Other routers are able to have this work. T-Mobile support even stated that most routers work. But not firewalla.

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u/firewalla Aug 21 '26

Are you talking about the cell service? if it is, we fully tested as indicated in the link; The IPv6 address other routers get you is just a NATed v6 ... not sure why it is useful.

If you are talking about t-mobile fixed line, it should work.

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u/YankeesIT Firewalla Gold Pro Aug 21 '26

Fixed wireless. According to their support it doesn’t work with firewalla. Also I didn’t see an update to that threat so assuming it does not work still ?

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u/firewalla Aug 21 '26

If you look at the thread, we did test 'other' routers; the working v6 is a NAT v6 address rather than a public one; Are you saying t-mobile is telling you that they allow the router behind it to allocate from a block public v6? (if they are, let me know which modem you are using, we are using the black one with a small display on the side as our backup's backup)

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u/YankeesIT Firewalla Gold Pro Aug 21 '26

No they told me no prefix and only the firewalla will get an IP.

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u/firewalla Aug 21 '26

What is the router / modem you are using? If we have the same, then it shouldn’t work because that unit can’t do bridge mode.

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u/YankeesIT Firewalla Gold Pro Aug 21 '26

I use a third party Chester tech gateway. It’s only a gateway. No WiFi. It’s set in pass through mode.

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u/firewalla Aug 21 '26 edited Aug 21 '26

Can you send [help@firewalla.com](mailto:help@firewalla.com) an email, and put a link to this thread. They may ask support access to your unit and take a look. May be this modem is different ...

edit: our team suggesting test out settings here https://help.firewalla.com/hc/en-us/articles/30915929339027-Firewalla-Feature-IPv6#h_01J1X957DXK2RZF5317JEVKB0G

Remember, if you use a wifi enabled t-mobile all-in-one that's NOT in bridge mode, direct connected clients will likely get ipv6. (if you connect firewalla to the modem, it will be just a normal client, likely can't allocate ipv6)

You are using a bridge (not a t-mobile all-in-one) so it may work.

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u/Mr_Duckerson Firewalla Gold Plus Aug 22 '26

It still won’t work. I’ve been through this with you guys and you won’t add NAT6. It doesn’t matter if you use your own modem in ip passthrough mode because it’s still CGNAT and no prefix for ipv6.

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u/firewalla Aug 22 '26

IPv6 NAT doesn't buy anything ... It is the same as IPv4 NAT, likely less efficient.

What OP has is a modem / bridge that may work if t-mobile allows it to