This was either the browser (Chrome) thing or something else. 63_2 does not have this problem.
Since Chrome has habit of upgrading itself without asking me i can't roll back to that version and check. @wocram - it is not as bad as it seems, all of those channels are very weak actually so they do not pose a problem.
Most of my devices at home use 5GHz anyway, you don't need 802.11ac to use 5GHz.