You will need to turn on media audio for the Grom. You should turn on internet access too.
On the Android Auto screen on the Grom, ensure that the 'Activate AAAuto UI' is set to automatic. You can tick bluetooth tethering if you want to use the phones internet on the Grom unit (outside Android Auto).
You must keep bluetooth switched on your phone to use wireless android auto. You must have wifi enabled on your phone too although you don't need to connect to any network as the Wifi connection for Android Auto is a background process.
I would suggest turning off your TPlink whilst you set up and demo wireless android auto to avoid any interference.
Make sure wireless android auto is enabled on your phone too. It's not enabled on some phones by default.
Go to settings, type android auto in search and open, if you see wireless android auto under system turn it on, towards the bottom you will see 'version', tap on it till you unlock developer options, click on three dots and enter developer settings, make sure 'add wireless projection to settings' is turned on.