weird internet issues

[BestBOTEU]

so a few days ago my internet dropped, with a weird error, i just restarted the router and it was fine, but the internet speeds sucked badly only on my pc, from 30-50mbp/s to 3mbp/s, the speed can be very incosistent jumping from 3mbp/s suddenly to 50 and mostly stay at 3 or 20, with the ping being normal, sometimes very high. on my nexus 5 its always 30-50mbp/s, on my ipad 2 its 20mbp/s too. all on the same wifi, nothing is being downloaded.

what could this be? 

thanks in advance

edit: i re-positioned the antenas on my linksys wmp600n and im getting 35-50mbp/s now pretty consistent for last few mins, this might have solved the issue, i will keep this post updated.