I know others have said this already but that may be the speed the RAM is capable of, but it’s likely more than the motherboard and/or CPU can handle. I built a new PC earlier this year and I also just relied on an XMP profile, and also had games crashing and the occasional blue screen. When I delved deeper into the BIOS and made sure the ram was set up to match my 13th gen i9 processor all those issues disappeared.
What is your upload speed normally? Copper DSL connections usually offer decent download, but they can’t provide much upload speed and it becomes very easy to max that out. Does work use Dropbox, One Drive, Google Drive, etc. to back up documents? If you’re maxing out an already slow upload then that would explain it.
Have you tested on any other devices to make sure it’s not just your Internet? We know nothing about your Internet connection but there are things that could happen to slow down the entire service.
Look around the house for ethernet and coax jacks? Coax for TV, ethernet for internet. Why would anyone here know where the other ends of any of that stuff goes in your house?
What are you talking about?