https://arstechnica.com/information-technology/2019/04/millimeter-wave-5g-will-never-scale-beyond-dense-urban-areas-t-mobile-says/

5G mobile networks have started arriving but only in very limited areas and amidst misleading claims by wireless carriers.

While all four major nationwide carriers in the United States have overhyped 5G to varying degrees, T-Mobile today made a notable admission about 5G's key limitation. T-Mobile Chief Technology Officer Neville Ray wrote in a blog post that millimeter-wave spectrum used for 5G "will never materially scale beyond small pockets of 5G hotspots in dense urban environments." That would seem to rule out the possibility of 5G's fastest speeds reaching rural areas or perhaps even suburbs.