How do I stay on n41 band on my trash can?

Thats good that it has taken focus on the single source. If the SNR is good and the RSRP are both strong enough it should be a nice solution. The n41 for sure will provide better bandwidth as long as it can get to the antennas on the router. From all the research I have done the SNR has a major impact. I worked in networking for 22 years so I understand the basics extremely well. If the signal to noise ratio is good to excellent that improves performance as there are fewer retransmissions due to packet loss and/or damage. It just makes sense. You might have a little lower signal power but if it is clean that can make all the difference. The n41 being a shorter, higher wavelength may not have the penetration but under reasonable conditions it can be a big win for the cost factor. Nothing will be perfect but T-Mobile is making some headway. 

I really believe many of the people that have cut over to the T-Mobile solution have their expectations a bit high. Going from a wired to a wireless/cellular solution is a pretty big jump in terms of technical demands. Many subscribers don't understand the technology nor have a good idea how to figure it out. It does require a learning curve and persistence. I worked with both wired and wireless gear for many years but even with all my experience I had to research and think through the cellular solution to get it to work well here. It takes more effort than most users want to invest. Once you have it zoned in it is a pretty good solution for the cost. I hope you can keep your lock stable.