12:09:56:WU03:FS01:Sending unit results: id:03 state:SEND error:NO_ERROR project:11758 run:0 clone:161 gen:0 core:0x22 unit:0x0000000a9bf7a4d55e6d770f4984c3b9
12:09:56:WU03:FS01:Uploading 55.24MiB to 155.247.164.213
12:09:56:WU03:FS01:Connecting to 155.247.164.213:8080
12:09:57:WARNING:WU03:FS01:Exception: Failed to send results to work server: Transfer failed
12:09:57:WU03:FS01:Trying to send results to collection server
12:09:57:WU03:FS01:Uploading 55.24MiB to 155.247.164.214
12:09:57:WU03:FS01:Connecting to 155.247.164.214:8080
12:10:16:WU03:FS01:Upload 0.23%
12:10:16:ERROR:WU03:FS01:Exception: Transfer failed
Yes, there's a known issue with WU 11758 and servers .213/.214, server/project managers are aware of the issue (but with the huge influx of new users the entire F@H team is working hard to ensure that there are enough WUs and that servers can distribute them).
There's more discussion about the issue in this thread: viewtopic.php?f=18&t=32492
There's nothing you can do to improve its chances of being uploaded. The client will keep trying periodically to upload it until it expires; the first time it tries to upload after the expiration date it will be deleted automatically. It won't interfere with folding other work units, so you can safely ignore it until it either uploads or expires.
There was a post from the developer in another thread that the problem was resolved. I checked my log & the work unit I had that was unable to upload did get uploaded before it expired.