OSMC on RPi3B inaccessible via WiFi network

My OSMC is no longer accessible via the WiFi network, no response to ping and impossible to connect via SSH.
I have power cycled several times but no go, still inaccessible.
If I ping from another RPi I get this response:

$ ping PING ( 56(84) bytes of data. From icmp_seq=1 Destination Host Unreachable

But the device was connected to the WiFi network as witnessed by the network page in MyOSMC when I use the TV remote in Kodi to check the system. The IP address shown above as it should be according to DHCP reservation in the router.
If I reboot from the Kodi menu the restart takes a very long time and ends up with a disconnected device.
It seems like the OSMC device now has decided to totally disregard the WiFi network.
If I move the RPi from the TV into the office where there is wired network available then it is not doing this, but then I cannot use it on the TV of courseā€¦

I have looked into the /etc/wpa-supplicant dir but contrary to other RPi (non-OSMC) boxes there is no wpa-supplicant.conf file there, so how is the WiFi connection managed on OSMC?
What can I do to fix this?

OSMC is using connman as network manager.
The config files are in /var/lib/connman

Here are the commands to connect manually

scan wifi
config wifi_<string of characters>_managed_psk --remove
scan wifi 
agent on
connect wifi_<string of characters>_managed_psk

But a sudden loss of functionality normally points to SD Card problems

I moved the RPi from the TV to the study where it can be plugged into wired LAN.
Then since I have an LG Smart-TV I can use its capability to show videos from a DLNA server on the network. This works for the viewing now since the Kodi system publishes the media that way and even though the RPi is now headless.
Drawback is that my programmed jump keys to skip commercials no longer work I just have to use the right arrow key repeatedly to skip 4 min forward.