Bad Upload Speeds

I recently switched from ATT to Cox because the upload speeds were better. I got the 50/5 internet. The general expectation is to get about half of the maximum upload. I am getting less than 1mbps(.6 to1, sometimes it even says 0mbps) on Cox's speed test. On speedtest,net i am getting 1.4 to 1.8mbps. on testmy.net i am getting .44mbps consistently. I did a test stream on youtube this morning to see the immediate fluctuation of the upload speed and it started at 3200kbps and fluctuated from 2500kbps to 3200kbps, after about 5 minutes it fell to 44kbps and fluctuated between 0kbps & 1100kbps for the next 20 minutes. Nothing was downloading or uploading during that time other than the stream itself. It should be noted that this was on an ethernet connection with wifi disabled on the 2-1 modem/router.

I understand that speeds fluctuate, but should they be going down to absolute 0 unless there is an outage?

Is there a reason I am not getting anywhere close to the advertised speed?