Chormecast Issues

So I am having issues connecting my tablet to Chromecast Ultra. I've tried both with and without the ethernet cord. With the cord it doesn't connect as it's doesn't find the device. Without it, it found the device up won't connect. It abruptly connects/disconnects. I cast it with the cast screen/audio button. I've tried rebooting both tablet and Chromecast, them FDRing the Chromecast, and reinstalling the app; all to no avail.

So my two questions are:

1: How to connect over hardline

2: How to connect without hardline.

My tablet's a Samsung Galaxy Tab SM-T280 Android 5.1.1. I don't know if it has a microphone but I doubt it does (can't find the option; the "Google Play" permissions don't have it). And yes, I looked at Google's guide.

Thank you.

 

I thought so too, but I chatted with other people prior to coming here and they said my tablet's fine. It can cast Youtube fine, Netflix, Hulu, etc.