Just to confirm I have 3 modules posting to a local MQTT server via a gateway on WiFi - all with latest firmware. The gateway hangs after 12 hours or so (usually overnight - ie it's hung in the morning, so I don't have more precise timing). Works after reset (module reset not needed).
Usually the green light is ON - that's how I know it's hung.
Just FYI, not a big deal yet, I'm still developing code for the modules.