Disk storage lockdown is enabled. You can check where this setting is on the following link. Basically disable momentarily the disk storage lockdown feature and you would be able to delete manually the .bkf files of expired backup sets.
Check the command given as a comment about moving the content folder:
“WSUSUTIL MOVECONTENT d:\WsusContent d:\WsusContent\movelog2.log –skipcopy”
Check forrest health:
Check any items remaining to replicate:
Last replication inbound attempt result:
Force replication on all controllers:
Force recalc by KCC:
Easy to follow instructions for Ubuntu:
How to secure room (conference) creation [Private Domain]
Check this website for file transfer time per bandwidth.
In this website you can get a Powershell Script that would do a WSUS server cleanup from the command line.