[luqman24]

I have the Linksys E1200 router and it's located in the living room upstairs where my ISP setup the Internet modem. Signal is great through the whole house but downstairs where the bedrooms are located is where the signal gets weak for some reason. I tried looking for ways to boost the signal on an internal antenna router online but couldn't find anything, all I could find was ways that would benefit people who have an external antenna router. So if anyone knows of ways of doing so, let me know because that would help me alot and probably many others who might be experiencing the same problem as me. I would buy an extender but they're pretty expensive where most of them cost more than what I paid for my router. With that being said, all your help and suggestions is greatly appreciated. And a big thanks in advance

[cleobrag]

Install DD-WRT on your Linksys E1200 router.
You can find very clear and simple instructions here:
Get more out of a Cisco/Linksys E1200 - Spiceworks

After having installed DD-WRT, you can go to Wireless -> Advanced Settings
and tweak up the Tx Power till you get a sufficiently good signal everywhere.
You might have to cool the router (using a small fan, etc.) when you boost the signal power.