R9000 - WAN VLAN Setting

Hello Community!

I posted this problem days ago in the Italian Community but no "reasonable" answer received.

So I'm trying here :)

In Italy if you need to use your Router with Fastweb (Italian ISP) with GPON fiber, you need to connect it to an external ONT via Ethernet.

The problem with the R9000 is that you cannot (as it seems) tag a VLAN for the WAN eth port.

Fastweb needs to have the WAN port tagged with VALN 835 and creating a VLAN tag group doesn't work.

It seems that the firmare tags the 6 "switched" eth ports and wifi ports but NOT the WAN.

I tried tagging directly the eth of the PC with VLAN 835 and connecting it to the ONT everything works well.

I tried also a 50$ router that lets you tag the WAN port and everything works.

It's incredible that a 400$ professional router doesn't have an option to tag directly the WAN port.

Anyone had the same problem? I read somewhere that there is a "custom" firmware from Netgear that enables it.

I wouldn't like to buy another router (not Netgear for sure), I would like to make it works.

I tried also dd-wrt but my linux / network competences are not leveled for that.

Thank you very much for any input or help you could give me.

Luca