Impossible to run freebsd-update

I have tried running freebsd-update about ten times over the last couple of days, both 12.1 -> 13.0 and 12.1 -> 12.2
and maybe 100,000 files have been downloaded (unless they are stored in cache somewhere after an unsuccessful update)
The update always finishes with the last file 'has incorrect hash' .

I can't believe this is a problem with the FreeBSD update server, because I have yet to experience such problems, so, what could be the cause and is there any way around his?
The file /etc/freebsd-update.conf contains a line : "ServerName". You could try to change this to something better, depending on the situation. Put a line "Components kernel" in it, to see if you can only update the kernel ,don't forget to remove it.
Try to run
freebsd-update -v debug fetch
And to see if name-resolution is ok:

The ways around, or upgrade from source , or build & install an upgrade server.
Building an upgrade server sounds interesting. I might give it a try if I can find out how to do it.

In the meantime, I'm tempted to simply extract kernel.txz and base.txz from 13.0 over the top of 12.1... I've already spent a couple of days trying to upgrade and can't see what harm I could do... It's only a home system...