@ScuffR thanks for your support, we are working in a very important project with great potential to scale and cannot seem to get it to work when there is no 2G connection.
I am confused by your last suggestion. You mentioned to use waitUntil() but when there is NO 2g connection we want to move on and write to the log to a SD (instead of sending it via MQTT). Therefore it seems we want to use waitFor which unfortunately does not seem to work with or without SYSTEM_THREAD. I am having similar problems than SYSTEM_MODE, SYSTEM_THREADING and loop(), waitFor(), waitUntil() except that for him at least without system thread it did work (at least came back after 327s instead of 60)