Wifi connected but no internet
So I bought the router recently and it worked fine for almost 12 hours but after that the the speed dropped to half my original speed of 100mbps on the 5GHZ band, taking the adapter off and putting it back in seemed to make it work again but now it shows wifi connected but no internet and no matter how many times i restart it doesnt work, direct ethernet connection to my pc works, but the wireless network does not. Also, the router is rated 12v 1.5a in the product description but the router came with a 9v 0.85a adapter is it ok or should i buy a 12v 1.5a adapter?