wifi mobile speed 369 mbps download.......Internet desktop speed 200mbps...using xfinity modern/router - ethernet out to netgear nighthawk. Desktop connected by ethernet directly to ethernet wall plug which goes directly to outside cable with splitter in garage . What do i NEED TO get desktop up to 400 mbps from comcast blast?
Update motherboard chipset drivers (Lan, USB family, Sata, pcie etc).
Depending on what's actually connected to the ethernet, age of mobo, or ethernet card, it's possible you may just need an upgrade. Old equipment won't necessarily be able to use the bandwidth and speeds of updated Comcast traffic.
Also check your splitters. For inet, there should only be 1 in line, that being outside at the main line connection. You can splitter cable TV up plenty, but if you have more than 3-6db drop due to cheap splitters, you'll see serious performance drops too.