Not sure if it’s still the case but the early RaspBian images for the RPi3 had wifi power management turned on by default which caused this unstable and bad working Wifi. I don’t know if max2play fixed that in their image (can’t check now) but it sounds like you were suffering from that.
You can check this by running:
And look for: “Power Management:”
You can change it by running the following to see if it makes a difference:
sudo iwconfig wlan0 power off
If it does, here’s more info on how to make it permanent http://www.modmypi.com/blog/disable-wifi-power-management but I’m sure max2play will (or have already) make it default in their image.
Funny, I’m slowly moving away from OSMC and OpenELEC because I want more then “just Kodi” and I prefer more flexibility 😉