I have the same issue, but lower speeds. I have one cable that will negotiate 100Mbit rather than the 1Gbps that I expect. For a week it has been 100Mbit only (

I have the same issue, but lower speeds. I have one cable that will negotiate 100Mbit rather than the 1Gbps that I expect. For a week it has been 100Mbit only (which is technically fine for the purpose), then two days around the router fell down and now I get 1Gbps. I suspect a badly installed or wrong choice of keystone.