Essentially the title.

For the past two months I have been experiencing absolutely horrendous upload speeds. I have the internet 300 plan and while I never expect to get 100% of what is advertised, it seems odd to not even get half of the 15 mbps upload that I believed my plan came with. Below you'll find images to two seperate tests.

First test 

Second test 

I have 2 devices connected via ethernet and I cannot understand what might cause this issue. Any help would be great thank you!