IP stacks have been fine for many years. There was some problems years back where some ISP's networks would have really crap internal IPv6 connectivity, so IPv4

IP stacks have been fine for many years. There was some problems years back where some ISP's networks would have really crap internal IPv6 connectivity, so IPv4 routes had much lower latency than IPv6 - but that was mainly bad network design and operation. All major operating systems have what's called 'happy eyeballs' algorithms to pick the best path for each connection. Apple updated theirs last year and reported that with most networks they tried, IPv6 was selected as the preferred option ~99% of the time it was available[1]. 1. https://www.ietf.org/mail-archive/web/v6ops/current/msg22455.html https://www.ietf.org/mail-archive/web/v6ops/current/msg22455...