When using chrome-cast with 5Ghz WiFi aka 802.11ac, it will refuse to connect when the current channel is between 52 (5260) and 144 (5720), despite that range being allowed to indoors with DFS/TPC in most of the countries. Does it have any reason, beyond laziness of google engineers?
Because it can´t verify if the router is complying with radar interference measures, chrome cast avoid these ranges. To correct this behavior, just use a lower or higher channel. Another thing, chrome cast uses your IP to determine the country, ignoring WiFi and google home configs.