Not getting appropriate upload speed

Hi Yall,
So, my promotional rate ran out and I changed my plan to save some money. I switched to the Gigabit plan from the Gigabit Extra for two reasons. 1. To save some money. 2. Whiled I'd loose 200Mbps on the download side, according to the plan information on the website, I'd go from 30Mbps to 169.62Mbps.

When the new plan went into effect, it shows in my account as only 20Mbps on the upload side. After the change, speed tests show a max of 23Mbps.

I reached out to support to figure out what was going on. I mentioned the advertised speeds on the website and what the plan was showing in my account and my speedtest results. They would not directly answer the question on the discrepancy. They did do some troubleshooting and then at the end blamed my modem as "Not being compatible and tried to steer me into getting an xfinity gateway.

1. My modem is in the equipment compatibility list. It supports Docsis 3.1. Supports Docsis channels 32 down x 8 up (there are modems in the list that are well below this spec).
2. A modem compatibility issue was never mentioned when I talked to the rep about changing my plan.
2b. When I was changing my plan, the rep told me the new speeds were 1000Mbpsx20Mbps. When I mentioned the advertised speeds on the website in the broadband facts the rep had no clue what I was talking about.

3. I mentioned to the support rep that I had critical errors in my modem.

I provided a screenshot of these errors for clarity to the rep and they completely disregarded it.

The rep also suggested I check with the manufacture. Manufacture specs for my modem show that its capable of 800Mbps upload. Yeah that's a result in the lab..but even if you half it, that's still higher than 2000Mbps plan which advertises a 306.02Mbps speed.

So what is actually the deal here? My download, despite showing 1000Mbps in my account, does actually hit the 1141.00 Mbps advertised on the website. 

Another odd thing, ever since I've moved here, the signal coming off the pole has been screaming hot and not one tech, both remote or onsite, has ever said anything about it. I added a 6db forward path attenuator and a splitter to get it down (it was down to 1-3dBmV depending on the channel and day). At some point in the last little bit, its gone up again and is sitting at 7-8.5 dBmV (depending on the channel) which means if I removed the 6db forward path attenuator it would be 13-14.5dBmV and higher yet if I removed the splitter. Don't get me wrong, I'd rather it be too high than low as its easier to lower it than it is to bring it back up. 

I don't suspect this is the problem with the upload speeds (the dBmV seems to be in the optimal range from what I can find).