Problems for Sky Fibre broadband users
The use of IPv6 versus IPv4 is usually totally transparent to many users and Sky Broadband is biggest provider offering a dual stack configuration for users, to the extent that we see lots of speed tests from Sky users on IPv6.
Alas this morning the dual stack nature may be confusing some as there appears to be a routing issue with Sky where IPv4 traffic for fibre (and maybe Sky Q) customers is getting lost but IPv6 traffic is still working.
Unlike the recent BT outage there is not (so far) a big spike in people testing their broadband connection, but one observation to make is that even though Sky has lots of IPv6 tests we are in an usual situation where none of the recent tests for those with FTTC/VDSL2 (fibre) speeds are on IPv4 (things may be improving as while writing this article some IPv4 ones are starting to appear, but still a long way below what looks to be the usual fifty fifty IPv4/IPv6 split).
Our speed tests run dual stack and will default to IPv6 based testing if it is available, but if you want to force an IPv4 page load for the test visit http://ipv4.labs.thinkbroadband.com/speedtest/.