I’m trying to set up a 2G Electron in an area with marginal cell coverage (marginal = -71 to -83 RSSI with Electron alone. Phone conversations work ok). I’m using the fixed PCB antenna from the kit.
When the Electron sits by itself with just the battery connected, it almost always connects to the cloud without a problem. But any of the following makes the connection very spotty (most of the time it fails to connect at all on boot - just keeps blinking green):
- Electron sitting in breadboard.
- With a DHT22 wired up (soldered directly on the pins with ~5cm wires with power from 3v3, no breadboard).
- Wired to a SSD1306 OLED monochrome display over SPI, also power from 3v3.
I power it from battery with plenty of juice. I put tinker firmware on it to remove variables, but nothing changed. I also tried putting capacitors in a few strategic places to no avail. It can’t be SIM or config/keys trouble since it connects and works fine without any of the other components attached.
I’m a software engineer so this is stretching beyond my HW abilities and into black-magic-land 
. My guess is that there is noise or something disturbing the GSM reception but I have no idea where to go from here.
Does anybody here have some good ideas?