Try setting the directory where you are trying to upload the files to 775(Apache/Linux) On IIS make sure the directory file permissions are correct.
the F5 logs are showing a double "HTTP 100 CONTINUE" response which causes the connection to drop.
What do the Coldfusion logs show? The issue might have to do with how you integrate Coldfusion and Big IP F5.
The permissions are correct and there are no event viewer security logs showing access denial to the folder.
I just replicated the issue and checked the logs and there are no log entries within cold fusion what so ever.for the instance that the action was performed on. The last log entry was from 10 minutes before the action took place.
Also the file I attempted to upload is not in the upload directory at all.
I went into IIS and then into HTTP Response Headers and turned off HTTP keep-alive under "Set common headers" and it looks like i was able to upload a file. I am having the field do the test now in hopes of them being successful.