New Gateway

As "Oregon" stated you can use speedtest.net to run tests and move the router about. That is helpful but locating the tower and knowing the reporting from the cellular signals is also important. If you get the RSRP, RSRQ, SINR values and the PCI info for the cellular signals then you can dial it in. You have to understand how the metrics work and how each value relates to the signal but a few searches on the web can help explain how the values work. 

If you get a clean signal i.e. with improved signal to noise ratio then you should see improved performance. If you see the SNR signal to noise ratio is poor then you know it may be a challenge. If you  locate the tower and have good distance to the tower without too many obstructions or line of sight then the SNR can be improved and the other metrics should as well. To some degree. It takes a little experimentation to dial it in. 

You might get lucky and find a good spot right away and get great download and upload speeds with low latency then it is not so important to go into the nitty gritty as to how it all works.