Exactly, PMTUD is unreliable because moronic admins block it and MSS doesn’t fix UDP traffic, does it now?
Solution (two in one, one for broken MTU and the other for an RFC4638 compliant ISP): Netflix and IPv6 - #11 by DarkNate
For fun, another member tried to find out where the 12bytes went as this is exclusive to MikroTik, he’s sent a bug report to MikroTik: Netflix and IPv6 - #11 by DarkNate