Streaming from Youtube and Amazon Prime (not so much Netflix) is starting to buffer on my 2014 IMac, usually about 10 minutes in. It is hardwired,32gb RAM, Radeon 4MB running High Sierra. I don't have this issue on my 2017 Macbook that streams with no issues over wifi. I've tried doing some research, but I haven't been able to successfully diagnose the problem. Any ideas?