How do i contact comcast about email problems?

For a few years i used an university MS-account with 2TB OneDrive storage. Now these cooperation runs out and i made my own MS account with those 1TB OneDrive storage. 

I have like ~500GB of data in that old OneDrive and right now try to copy everything to my new personal one... But the uploadspeed is horrible! Referring to speedtests I have like 50Mbit/s (Ethernet so quite stable) so ~ like 6.25MB/s upload. The maximum onedrive reaches is like 1.5MB/s.... and in average i get like 750kB/s...

My PC is already running for 2 days...

Do you have any idea to solve this problem or is this just something i have to accept?

Is it possible that institutions like universities have better uploadspeeds, or are just prioritized and so on?