Shovon99, I would need to get additional information regarding your system.
So, please let me know if this is a new integration on your system?
If not, please let me know if this Intel® Dual Band Wireless-N 7260 used to work?
Which Operating system are you using?
Which is the model number of your system?
I am using a new Acer Aspire s7 392 9890 upgraded to windows 8.1. The internet works fine downstairs but becomes really slow when its upstairs, meanwhile my old Dell Inspiron n4110 running windows 7 works about 3x faster using the same connection. Current wireless driver on the acer is 16.6.0.
What band you are using to connect the Intel® Dual Band Wireless-N 7260?
Then, which band are you connecting the other wireless adapter?
Where is the router located?
Just in case, this is the latest driver available for this adapter in our site. You can give it a try.