I've had very slow uploads all day today and files are taking considerably longer to upload to Youtube / Dropbox / FTP servers when they normally take seconds. A 50Mb file is taking about an hour to upload to Youtube at the moment.
I've done speed tests at Ookla and BT Wholesale but both of these say that my upload speed is about 16Mbps.
If anyone has any suggestions for fixing things, I'd be very grateful. I've restarted my router / computer and tried another machine but haven't had any success so far.