Both my systems can't get work. Both still have a WU that won't upload and will expire on the 25th.
a) Can't get workMy logs are all saying No WUs for this configuration. So are the servers up but out of work?
This is currently a very common problem. It is because Folding@home's COVID-19 work was featured in various media by now, and a huge number of individual users as well as several IT companies have brought clients online. The F@h servers can't distribute work as fast as it could be taken on by contributors right now. The F@h project has already added more work servers during the last days, and presumably is in the process to add even more.
The client automatically retries the requests for work. But the more tries, the longer the delay between each try. If these delays get too long for your taste, you can either shut down and restart the client, or pause and unpause the client, or pause and unpause the individual slot. The next retry delay will then be ~1.5 minutes or less.
b) Stuck uploads
This is a common problem. I had some of those myself during the last few days, and am having one right now. Just let the client retry to upload them; this does not interfere with the requesting of new work or the execution and upload of other work.
Edit: See @biodoc's answer below.
c) No WUs for this configuration
Could be one of the error messages which are caused by a). Or you may indeed have a slot configuration to which none of the currently available work fits. Is this a CPU slot? If so, how many threads are configured for it?