IPv6 not working on router

Hello all,

I have configured a wireguard tunnel to WARP+ using wgcf. It works perfectly with IPv4 but IPv6 is not working. I did a packet capture on the Wireguard virtual interface and I can see IPv6 pings going out through the wireguard tunnel but there is not a single packet coming back. IPv4 flows back and forth, no problem there.

The same WARP+ account passes IPv6 pings to the same destination just fine on my desktop.

Hence I’m wondering what the router is doing wrong. The source IPv6 of the packet is the correct interface IPv6, I checked.

The only thing I had to do that is not following the Cloudflare config is that I configured the interface’s IPv6 with a /127 mask, instead of a /128. But the IPv6 packets sent do not include this information, that’s just config on the interface, hence I currently don’t believe it’s the cause of the issue and I’m just mentioning it to be thorough.

If anyone has an idea what I can do to narrow down the problem, I’m all ears.