Problem uploading video from MacBook Air 2020

I am trying to upload a short video to the Udemy platform from my MacBook Air 2020.

This is via wifi and phoneline broadband (not cable) internet.

I am new to this sort of thing and thought it would be fairly easy. But, when I upload it starts, but makes incredibly slow progress. I waited for hours and it just wasn't getting above a low percentage of upload.

I contacted Udemy to ask what to do - they suggested uploading to wetransfer.com. I had the same problem there - so I know the problem is my end rather than theirs.

My wifi is OK for standard internet searching and to stream TV.

The video I am trying to upload is an MPEG-4 movie of 340MB - just over 2 minutes. So I don't think that's a huge file is it? How long would you expect it to take to upload?

I'm wondering if anyone has any ideas for me.

Best idea I have come up with so far is to buy an adaptor so I can connected my laptop via ethernet cable to my modem. Is that a good idea?