1. Please share your debug info log so we can see exactly what the third IP is assigned to.
2. Manually closing ports or removing parts of Max2Play is not recommended or necessary. As you can see in the Health Checker under Settings/Reboot, the system already runs well. Kodi is just installed and never has to run if you do not need it.
Another tip: The Pi3 shares an antenna for both WiFi and Bluetooth. So if you want to use both simultaneously, utilizing a WiFi dongle would be recommended.