It is simple.

Most boxes incl tx3mini, tx5max, u can set BOTH ethernet and wifi ON.

Ethernet takes priority, wifi is actually not adtive.

That way, the app is "fooled", will allow the lan connection to work.

Just use official tmpad version, no problem.

if yr unifi pack does not come with STB, the only way to watch playtv is with yr own device.
u just need the id and pw provided by them for this purpose.
what u can get with that id/pw depends on what pack u paid, aneka, varnam, ruby, ultimate... i m not sure if the pack names have changed...
by "premium", i think u mean the biggest pack, ultimate.
sure u can get all of them on playtv, but don't expect the highest quality... they are not as good compared to STB.

tx3mini at rm120 or less is probably the cheapest box there is that can do playtv@unifi and astrogo.
best to get the 2/16gb model rather than the cheaper 1/8gb.
u just need to close the root under settings, install playtv@unifi (tablet) from playstore.
key in yr id/pw, ur go to go!

If I am not mistaken, another requirement to run Unifi without error is to keep Android WIFI setting turned on even if you are using LAN connection.

This is what I understand of the earlier posts written from the tx3 expert (sorry forgotten the expert name :-p) and AVFAN.

Something else I found out :-

And NEVER NEVER, Open the Root setting again. Otherwise you would have to clear cache/data of the OFFICIAL version Unifi App as you will receive permanent error on root detection. And you will need to login again. If you are not comfortable with keeping Root Setting closed permanently, then consider getting a modded unifi apk of older version.

The two part solution mentioned by SCThong is with regards to AstroGo whereby a modded apk is required.

For Unifi, you can use the official version from playstore. You just need to avoid the two types of Error that can be detected by the official app.
Wifi detection and Root detection.
- Keep Android Wifi setting on always.
- Permanently Keep Root Close setting. (otherwise you will need to clear data and cache and relogin to Unifi)

Netflix no problem.. should work fine

There are two version of official netflix, one is black background logo, one is white background logo. The black one cannot do 4k and so should not have problem installation. The white background netflix have very stringent requirements which I don't think tx3 mini can meet.

Also there are many fake netflix.

The official one package name is com.netflix.mediaclient ( black ) and the other one is com.netflix.ninja ( white ).