Consider a booster for your router. I have one setup up that sits atop of mine and it was not
hard to install. Got it at best buy, but any place that sells hardware should have one. My computers are downstairs in a den and my signal is not as good as my hubby and sons
game room/ office. But our modem and router is upstairs .
You can ask your cable co to check signals,they will also come out to check, they can install their own booster, or check to see if anything else can be done. Update firmware for those pieces of hard ware. Sometimes that's why a new modem or router works better, it came with the newer firmware. This happened to my sons with a particular game. After I bought a new router, they had no problems. However, the game forums had many people who fixed the problem with a firmware update.
Also consider how old all of your equipment is. From modems to receivers . Time goes quickly, but technology blinks.
Before you do any of this make sure you know how to do it and un-do it. You tube is great. Many people put up ins videos for how to fixing. ( even tho I've worked with computers since DOS, I still need and appreciate any help)
Also google items and forums . Just as you've done here. There's always someone out there who has or had your
problem and may have a lot of info to offer.
If this is the only computer you have a problem with, tell dell that too.