my home is MESHed and signals are decent so may not help.
MESH signal strength is decent when measured from devices that have good antenna's. RPi boards have rubbish antenna's so the assumption may be invalid. Lots of random issues magically go away when WiFi things are moved closer and/or people give up and move to an Ethernet connection.
The system log shows that Kodi starts before the network is up so background checks Kodi does on startup might prompt the "no route to host" error. WiFi connections are often slow to come up so you might need to increase the wait-for-network time in the LE settings add-on.
The connection manager (ConnMan) is configured to prefer Ethernet over WiFi, so if Ethernet is connected and the interface has an active IP address, Ethernet will be the default route. You can also have a WiFi connection active at the same time but this will have a lower interface priority and will not be marked as the default route.