Connection to Airport Wifi

Recently, I have travelled through Doha International Airport (Qatar) and Colombo Bandaranaike International Airport (Sri Lanka) with one of my friends which we have different iPhones (Xs and 12 Pro) both updated to the last version of iOS (14.7.1) but both of them not connected to airports free wifi. it shows after connection to wifi need to access to the login page and in the browser page addressed as: captive.apple.com but the login page never displayed! several try , Phone reset, Clear Safari history and reset the network setting was unsuccessful for connection in both airports but our Laptops (MacBook pro Early 2015 -macOs Big Sur Version 11.4) connected easily to Airports free wifi. just i updated it happened in Dubai International Airport (UAE) when my friend going back but his old iPhone (iPhone 8) which iOS has not updated (version of iOS 14.5.1) connecting to Airport free wifi while same error appear in the connection with iPhone 12 Pro.

Could anyone please explain what is the problem and which type of setting need to change?