The RDP file downloaded from RDweb on some servers gives gatewayusagemethod:i:0 and some other servers gives gatewayusagemethod:i:2.for same application

I have a requirement where i am suppose to publish my application as Remote App on RDWEB. Initially the rdp file downloaded for this application had value for "gatewayusagemethod:i" as gatewayusagemethod:i:2. and the application was getting conneted and launch perfectly. Recently we tried with some servers of same configuration and it as observed that value for "gatewayusagemethod:i" as gatewayusagemethod:i:0. I googled and came to know that 0 stands for "Do not use an RD Gateway server". and 2 says "Use the RD Gateway if a direct connection cannot be made to the remote computer (i.e. bypass for local addresses)." 

Just wanted to know

1) what might have caused this change, any way or configuration to avoid this change keepgatewayusagemethod:i value consistent? As in future i will have to create the RDP file programatically.

2) what impact will i have if i use gatewayusagemethod:i:4 value ? will my launch be impacted on any of the servers? ,Can we use the Remote app even if we dont use RD Gateway?? 

Thanks in advance.

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