IPv6 doesn't seem to be affected by this.

If you don't have native IPv6 from your ISP, you can use an IPv4 to IPv6 tunnel to add this functionality yourself (Idea from this guy).

Just register on Tunnelbroker (it's free) and make a new tunnel with your public IPv4 address. I had to disable a Firewall setting in my router for them to be able to ping my address.
Then, configure your Linux distro to use that tunnel. I use Arch, and it was straight forward for that as explained in the Archwiki . I used the first method by creating the service and just replacing "server_IPv4_address" and "client_IPv6_address" (provided after creating the tunnel) and "client_IPv4_address" (I had to use my local 192.168.x.x IP).
Then, just start WoW, go into the options and active IPv6 and it worked for me!