DNS Error

So my Internet provider is Comcast. Xfinity and my Internet has been not wanting to connect all the time only when it feels like it I’ve tried everything on Google to possibly fix this including resetting my whole entire computer and also getting a new modem from Xfinity and normally my computer is pretty quick at loading everything but lately it hasn’t at least when it comes to browsing on the web it’ll either load really slow or just not load at all and say have a DNS error, also I game a lot so when I open battlenet and it will connect disconnect reconnect disconnect, reconnect over and over again I don’t know what to do anymore. The stuff that’s connected through Wi-Fi works perfectly fine for my computer itself is hardwired in and doesn’t work.