Wifi from AirPort Express (2) base station not connecting to iPhone17 Pro

AirPort Express A1392 Base station (second generation) is connected via ethernet to the router. The AE has been factory reset. The phone software is updated, turned off and back on. My 2019 MacBook pro connects fine to the internet with excellent strength via the AE. In settings on the iPhone, it looks to be connected to Wifi, as I get the blue tick next to the correct network, but there is no Wifi symbol at the top of the phone that would normally replace the 5G symbol and I can't get online.