It’s not just their NAT64 that is problematic. I have a business 5G internet account with them and it is useless with a VPN. They throttle any kind of VPN, Proxy, etc. down to about 300 kbps and interfere with it to the point it is unusable. You can surf the internet or even use it for some VoIP, but overall, it is complete crap. Also, I get a static IPV4 address and IPV6 is excluded completely from my account.
Great suggestion as it’s gotten me a few times 
But I think that box appears at an earlier percentage than 98. There’s an article out there that states what each percentage failure means.
Having the client try this today as I’ve seen it a few different places.