Some types of WU's Nexrad radar are down right now, including type=N1R and type=N0Q. Type=NOR (base reflectivity) disappeared permanently last May, as discussed in this thread:
https://www.wxforum.net/index.php?topic=41974.msg429340#msg429340. Some forum members switched to NCR then, although N1R and N0Q also were options.
I was using N0Q but it quit working on Feb. 18, although I checked and saw it was working in other places. I switched back to NCR (composite reflectivity), which continues to work. Then I noticed today that N1R and N0Q apparently quit working yesterday. So, as far as I can tell, the only type that continues to work right now is NCR.