Are you sure your old Dell is able to use the 5.0 GHz band? Apparently not. Then it's a hardware limitation. A 5 Ghz capable USB WiFi dongle might be the solution.
About a week ago I decided to return my rented Comcast modem/router combo and buy my own modem/router combo. I settled on the ARRIS SURFboard Sbg6580-2. The new modem is in the lower level of a split level house and I noticed that upstairs the Wi-Fi signal wasn't great and decided to do some tinkering (my first mistake). I remember that my old Comcast rented modem had two settings - 2.4 and 5.0. The former reaching farther but having a slower speed and vice versa with the latter. When I setup my new modem, the ARRIS, I only setup one connection and assumed it was 5.0. I set about this afternoon trying to figure out how to get both 2.4 and 5.0 to switch automatically back and forth on my phone, iPad, etc like it did with the rented Comcast equipment.
Following the instructions from the ARRIS manual, I typed in 192.168.01 and discovered that my connection was only 2.4. When I changed it to 5.0, boom, no internet on the laptop. Doesn't even show up as an available network anymore. It's seemingly gone completely and I have no idea how to get it back. The laptop is an old Dell xps l502x. I've tried restarting the modem and laptop but still no wireless signal.
Any suggestions or explanations on what is going on here. I can still get Wi-Fi on my phone and iPad but not the laptop I was messing around with.

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