New Onn plus causes t-mobile WiFi issues for all devices

We have had no issues with our internet since we got it in December. I set up a new Onn plus device on a new tcl tv two nights ago. Added stremio with real debrid according to a guide on this subreddit & SportzX app.

The next day my mom started having connection issues on the computer, unplugging & replugging t-mobile gateway router seemed to work.

Today it’s not working & I noticed my phone is also having issues with connecting to WiFi. I tried trouble shooting with no success, finally unplugged Onn box & tv & now we are back with no issues.

Is there a way to fix this or am I destined to walk the plank (no pirating Onn box)?