I'm having issues with this router and IPv6 with my Android phone - I cannot get an external IPv6 connection.

 

I've been down a rabbit hole with this and think it may be due to a low RA, but I can't change this.

I know this router is an ISP-only model, but I bought this from an old ISP who don't exist any more, so I don't have a support option to go to with them.

Is there a fixed firmware for this router?

 

IPv6 test on PC connected via Ethernet IPv6 test on phone connected to same router