Which image are you using in your board?
Before using connmanctl, try running:
root@edison:/# systemctl enable connman root@edison:/# systemctl start connman
You can have a wired and a WiFi connection to your board in order to have back-up network to connect when one it's down. But you only can use one at a time.
Slowly getting up to speed using connman with my Edison. I've managed to enable a static IP.
What I'd love to be able to do is have both a wired ethernet connection over a LAN
a wireless WiFi connection for further debugging.
Is is possible to have 2 active connections to the Edison like this?
in principle, yes - however, typically connman is activating only 1 connection (in the a predefined order - by default 1. ethernet, 2. WiFi with strongest signal ...). If you'd unplug ethernet, WiFi would jump in ... I haven't yet found a setting which would make connman automatically connect ethernet AND WiFi.
However, what is definitely possible and I have used it frequently is to manually (or via script?) activate WiFi even if ethernet is already connected.
Also am having a problem simply using connman to connect to a wifi network
$connmanctl enable wifi
to first ensure wifi is enabled
to get a list of available wifi networks
$connmanctl connect <servicename>
but get an error
Error <servicename> Not registered
maybe not quite intuitive from the documentation but you need to switch on the agent first once you intitially enter security data (unless you manually put them in connman config files)
i.e. to initially register a WiFi hotspot
connmanctl> agent on
connmanctl> scan wifi # you may need this if you don't initiallly see the hotspots
connmanctl> connect <servicename>
Once a hotspot is set up with all security data you'd be able to connect the way you tried in the future