My intenet connection is very slow due to ...

This mentions Linksys, but it relates to all routers

Intermittent Connectivity:
NOTE: Before following the steps in this article, check if your wireless computers have stable connection when connected to other wireless networks (hotspots).
This article assumes that all wireless computers are experiencing intermittent wireless connection with the Linksys router.
Frequent wireless disconnection can be caused by different factors such as:

1. Wireless interference within the network.
2. Wireless settings of the Linksys router are still set to default.
3. Firmware is corrupted.

Reducing Wireless Interference
If you are experiencing frequent disconnection from the wireless network, it helps if you check the following factors, all of which can greatly affect your wireless signals:
your cordless telephone system (or even your neighbors’), or other nearby equipment. Try to change your router’s channel to 1 or 11 (the default channel is 6) and restart the wireless computers.
Physical obstructions: Your router or wireless computers may be losing connectivity because of physical obstacles such as walls and floors. Try to move the equipment to different locations to find a better link.

• Placement of the router: Linksys suggests that you place your router as high off the ground as possible. When placing the router in a high location, leave a distance of two feet between the router antenna tips, ceiling, and wall. If your signal passes through multiple floors, place the router on the upper-most floor, and high up in the room.
• Surroundings: Keep the router away from large metal objects, bodies of water (fish tanks, bathrooms), and any electrical equipment including television sets, microwaves, radios, etc.