One computer on wireless network slow and dropping out.

Hello, how's everyone?

I have been having an issue with my wireless network for a while now, and have not been able to find a permanent solution. I have two computers in my house connected to a wireless network through a router which is connected to a wired modem. I've had my setup like this for some time. However, the connection on my computer has been slow as of late, and drops out at least a few times a day. The upload speed is dramatically slow as well, while the download speed fluctuates between good and bad from time to time. Whenever my connection drops, it usually fails to reconnect and I have to delete the network from my computer and discover it again. The network is not hidden. Doing this temporarily solves the problem though it repeats itself sooner or later.

Connecting my computer directly to the wired modem solves most of these problems. However, the connection drops when wired as well, though not as frequently.

The other computer has none of these issues, and I've ran comparison tests between my computer and the other computer. It's clearly visible that it's an issue with my computer.

My computer is virus free, I should add. Malwarebytes, Spybot and Avira scans always come up clean save for some occasional tracking cookies.

Any help or advice would be greatly appreciated. I am not a computing novice by any means, however not an intermediate expert when it comes to networking.

My router is a D-Link DIR-300, while the computer in question is a HP Pavilion DV5 laptop.