@TP-Link Can the Wifi module be replaced? Is it something I can do myself or do I have to send it for repair?

My wifi has gone. No device I have displays the SSID. WiFi light is on, it is configured correctly... but the SSID simply does not display. I used to be able to do a hardware reset and reconfigure...

@TP-Link This has just started happening to me with the new SIM card I was provided with by my new ISP. I've had my MR6400 for years and used a number of different SIM cards, all with no problem...