Wireless works only when right next to router!

My wireless only works when I am right next to my time capsule modem. This started happening since I updated to Yosemite some months ago and I have tried to problem solve it with no avail. Any ideas why the wireless only works when next to modem. There are known wifi issues when upgrading to yosemite however although tried all the suggested solutions have not yet solved the problem, I believe I might just need a new wireless adapter (something wrong with the antenna maybe?). Or should I try a clean install of the new operating system?