WSUS Sync failure

I take it since you're importing it, you've set the proper SchUseStrongCrypto for .NET?

If not, run the following from an Admin PowerShell Prompt:
New-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft.NETFramework\v4.0.30319" -Name "SchUseStrongCrypto" -Value "1" -PropertyType DWORD -Force

Yes, this happens with SchUseStrongCrypto enabled (and disabled too).

Also, have you changed the URL to

http://catalog.update.microsoft.com/... &Protocol=1.8

https://techcommunity.microsoft.com/t5/windows-servicing/known-issue-with-importing-updates-from-the-microsoft-update/m-p/163830

Mine already uses 1.8

I'm trying to import updates using PowerShell, but since I activated SSL I'm not able to connect to the server anymore.

How I used before SSL:

[reflection.assembly]::LoadWithPartialName("Microsoft.UpdateServices.Administration") | Out-Null
$WSUS = [Microsoft.UpdateServices.Administration.AdminProxy]::GetUpdateServer()

What I'm trying now:

[reflection.assembly]::LoadWithPartialName("Microsoft.UpdateServices.Administration") | Out-Null
$WSUS = [Microsoft.UpdateServices.Administration.AdminProxy]::GetUpdateServer("server.domain.local", $false,443)

Any ideas?

That link reads mostly like a recommendation is to go to WSUS 4 or above doesn't it ? (so assume that is Server 2012R2) . Can you say where it mentioned version 3.2.7600.226 ?

As a side note I have a version 3.2.7600.307 that is failing with a 404 error.....

Yes it looks like they suggesting to upgrade to 2012R2 as for the most people 2008R2 is out of support (we have extended support) hence the 2020 January out of support for WSUS 3.2. Waiting for MS to confirm this with the escalation engineers.

Question: how did you get to 3.2.7600.307 - can you remember the hotfix you applied to get there?

We are on:
Server 2008R2 SP1
Wsus 3.2.7600.226

Also I've tried following this article:
https://learn.microsoft.com/en-us/troubleshoot/mem/configmgr/wsus-synchronization-fails-with-soapexception

and changed to the following:
$config.MUUrl = " https://sws1.update.microsoft.com"
$config.RedirectorChangeNumber = 3011

with a new error in wsus:
an http error occurred:
WebException: The underlying connection was closed: An unexpected error occurred on a send. ---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

When reverting back to the original setting:
$config.MUUrl = "https://sws.update.microsoft.com"
$config.RedirectorChangeNumber = 4002

Back to the previous error:
Unable to resolve the specified upstream server name:
WebException: The request failed with HTTP status 404: Not Found.

Ive been trying to puzzle that one out too - I was trying to get my lab to the same state, but highest i've reached there is 225.

The last update installed on the 307 server was KB4484071, but think there must have been something else that has incremented the version without showing in the installed update list....bit confusing that one!

Strange thing this morning was that for a time we started getting Certificate chain errors during the sync (instead of the 404) , but this afternoon it has gone back to 404. (And I havent altered anything since yesterday - and then only bouncing the service)