I have the internet connected to a computer 2 rooms away(sm…

Ah that will cut your signal.

Can you run a cable to other room or use a range extender?

To be honest you should use a wired connection if possible. Wifi can be affected by a few things such as interference from equipment that is close such as a cordless phone or microwave. Also the channel that the transmitter is on could clash with another transmitter that is close.

A range extender is put half way between the wifi transmitter and your computer to help extend the range of the wifi signal

Here is a good range extender

Yes being connected directly is always best. The extender is another transmitter in your home and can be put closer to other equipment to service it.

It literally extends the range of your wifi network

Do you have cable TV in your home?

Is your Internet from your Cable TV provider please?

You'll get better signal but hard to say how much

Ok can I suggest that you call Comcast to see if they have a MOCA option which uses your Cable TV wiring to carry your Internet signals if it'll be hard to run a cable from your router to the other room

Please read this

You leverage the cable TV wiring in your home to carry the Interent signals for the main computers and then you can use the Wifi for your peripheral devices

Thank you if you look at the bottom of the page it shows if it is MoCA capable. That's what you need to ask Comcast about.

To conclude you need to connect your other computer by cable to your router

Thank you and Happy New Year!

Here's some more information