Thank you for your response, Aart! It's good to know that I am not the only one experiencing this issue. I am positive this is an issue with the Surface 3 as I currently am on my third Surface 3 LTE (because the first two got replaced due to screen issues)
It would be nice to have the option not to use the HSPA+ band. I think now it sometimes switches to the HSPA+ band because the signal strength of LTE is not as good as the signal strength of HSPA+. Not saying there is no LTE signal at all...just less powerful.
In those cases I would like my Surface 3 to hold on to LTE rather than switch to a band with better signal that provides no internet.
Still sometimes internet over HSPA+ is fine...sometimes...
I don't think there is a way to force this as it is really hardware level settings and scripting.
I wonder if the Samsung Galaxy Tab S Pro or the Dell Venue Pro (which both have LTE options
as well) are any better at this. In hind sight I think the Dell would have been a better option. I notice that I use an Archos Cesium 80 (very cheap 8" Windows tablet) a lot at home while on the couch. The only huge advantage of the Surface 3 and the 10.8"
screen size is that I don't need to carry a separate laptop. And I think the sizes above 10.8" are too large.
For that matter the Chines stuff that comes from Aliexpress, Gearbest etc may also be a good option. iPad sized casing, running Windows. With LTE options, keyboard docks and stylus support. But...you cannot be sure if it is really what you want.
I own an EXOPC and WeTab tablet. Both have a Huawei EMM770W card that allows 3G connection. However, with those you need to dial in every time you want to get on the internet.