Read here on the WSUS Team Blog a nice article about troubleshooting WSUS. It references the site https://www.wsuswiki.com/.
This site was created to provide a place for the WSUS community to share information about WSUS, including troubleshooting steps and best practices. The advantages that this site provides over public news groups include:
- Content on this site is edited and kept up-to-date. News group postings can get out of date, can contain incorrect information, and are often not corrected.
- It is easier for readers to find information on this site than in the news group.
- This site captures minor contribution from many users and both aggregates and persists them over time. This body of work grows and gets better over time whereas newsgroups just grow.
- It is fun to edit pages and improve on contributions of others. You can not really do that with news groups.
It also references several troubleshooting tips for successful configuration of WSUS. Check it out.