[strongSwan] Upgrade to 5.6.3 breaks Windows 10

[Tobias Brunner]

Hi Christian,

> *IKE authentication credentials are unacceptable. The error code
> returned on failure is 13801.*

If you send the same certificate then this is strange.  Did you try
going back to 5.6.2 to verify that it's actually caused by strongSwan?
Otherwise, I'd assume the reason is a Windows 10 update (or upgrade e.g.
to v1803, which apparently brought some updates to the IKEv2 client as
IKEv2 fragmentation is now supported).  In which case further analysis
is required.

Regards,
Tobias