I've been running an MQTT Arduino sketch with no problems. Connected to my router fine. Then yesterday it just wouldn't connect. Status is WL_DISCONNECTED after the WiFi.begin(). I've put a very simple example sketch back in and still no connection. It WILL connect to a hotspot created by my Android (22.214.171.124) Sony Xperia X phone.
My router is odd in that it is a MIFI router and it doesn't come with much in the way of configuration options. Let alone a connection log. It is a Huawei R218h.
I should add that I have another Heltec Kit8 running exactly the same sketch and that connects fine.
I've tried various code suggestions but with no luck. Anyone ever seen anything similar?