oss.sonatype.org is having significant network problems and has been for at least the last 5 hours, although I experienced the same problems yesterday as well. The sonatype ops twitter account recognized this earlier today:
It looks like oss.sonatype.org is buckling a little under the volume of staging operations. We'll investigate, though it may mean intermittent restarts as we tweak the configs. Feel free to create an OSSRH issue to have something to track.
It is unclear to me if a fix for this is in progress or not.
Also, do you guys have a status page (like status.sonatype.org or similar) so I can be aware of operations work you may be doing and not bother you with OSSRH tickets?
Anyway, thanks as always for your continued (amazing) support of Maven Central and the extended dev community!