Internet - Vastly different speeds iphone12 vs Galaxy S6

True I was considering the possibility that the Galaxy Tab S6 might have been using LTE because it is an option for that device and it is only LTE at best. If a test was conducted by disabling the cellular on the Galaxy Tab and it was connected to the T-Mobile WIFI then it might or might not get more similar results. The optimal servers seems to be quite different for various devices and hardware and drivers etc… can for sure impact results. Sometimes it seems a test right after another can also provide quite different results. It is interesting to use multiple tools for speed testing. Testing to see an average and at different times of the day/night can help better profile the operation of the solution.

I still feel it is best to know the cellular metrics so expectations are possible. The LED bars are generic and just don’t provide sufficient information. It all takes a bit of time to pick it apart.

“Which speed should I use to determine if I should keep T-mobile internet?”

I would not decide upon just upon speed as that is going to fluctuate depending upon the time of day or night. Of course if the decision was upon speed then those from the iPhone of course would win hands down. If you record the metrics and can see the signal strength, quality, and signal to noise ratio are all good to excellent in character that is a good sign. You just need to determine if the service meets your needs. If you are not satisfied with the level of service or dealing with the cellular is more than you want to deal with then it is personal preference. I find it hard to beat the T-Mobile solution when the signal is stable and the download and upload speeds are improved over prior solutions for less money. No hidden fees, no contract and being able to walk away is not a bad thing. Just things to think about and consider. I hope some of the observations and suggestions help. 

Below is a chart that explains the cellular metrics.