After 2 weeks working perfect, last monday my mkr 1310 stop connecting to TTN v3. In the TTN console, 'live data' tab, the only feedback is the 'Accept join-request'. I upgrade the firmware (now ARD-078 1.2.3), update all lib's and run several and diferent sketchs but nothing change ... allways the 'Accept join-request' because the "int connected = modem.joinOTAA(appEui, appKey);" is allways false. I do not have access to the gateway, but I already try in 2 diferent locations with 2 diferent gateways already used in the past.
I removed all the sensors from the hardware, the mkr is "clean" now.
Running out of ideas ... need help. I'm beeing blocked in the TTN or is an hardware problem?