@mimmo wrote:Thanks @Luddite I knew someone here would have the solution.
What do you mean less stable? Is that because of towers etc? Is this an apple thing or Android as well?
It depends on location and what the LTE tower frequency is. Most phones hang onto a connection for dear life even if it is struggling to get a strong connection. This is what causes data performance issues.
With band 4 (1700 Mhz) being the most widely available band in many areas, the relatively high frequency means a potentially weaker connection in an indoor environment. Quite often, selecting 3G will result in a band 5 (850 Mhz) connection which is generally more friendly for indoor signal strength.
These are all generalities and can vary widely depending on location specific conditions such as the available LTE bands. Out in the GTA, Bellus has invested significantly in repurposing both band 2 and band 5 for LTE-A as well as making use of the 700 Mhz spectrum. In these locations, there are no real advantages with 3G vs LTE connection.
On android, I use network cell info lite apk to do site surveys of areas I spent a lot of time in like home and work. Right now I have a band 13 connection which is a 700 Mhz frequency band. This is arguably even better than band 5 on 3G. Long story short, I would recommend against universally forcing a 3G connection, especially when the setting may be left on and forgotten. Maybe the user is not holding the phone correctly? 
