The two that failed were 176 MB and 197 MB. The other two that went through were 85 MB and 107 MB.
I attempted to upload the same four files together to Acrobat cloud. I did not get a fail, but only one of the files is showing in the Acrobat.com files from today. The others are showing dated yesterday, but with a (1) after the filename.
Upload speed is 5.5 Mb/s