Hello and welcome!
Sorry about the delay! Please do the following:
Please check below registry value:
HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\WindowsUpdate\WUServer
HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\WindowsUpdate\WUStatusServer
If these registry value point to old WSUS server, delete them and then run “gpupdate /force”. Check above registry value again.
Make sure you have a good backup before trying this!