Hi, check that your 7520 has the latest firmware installed.
Here is the link on how to check it.
What operating system are you using on your computer?
What is the name of the router\model providing the WiFi?
How far is the 7520 from the router?
Is the 7520 connected directly to a wall power receptacle?
See page #47 of the 7520 users manual on how to connect the 7520 to your WiFi router.
How many computers do you have using WiFi?