Network search has been reported to give problems in some circumstances but if it works for you then that is good.I couldn't help but set the "network search" option to "on".
Basically, I just selected the HD channel, with DVB-T2 selected and it happily went through all of the channels for the relevant transmitter.
119 channels found after 1 manual scan.
Your guess would be wrong; it will work without an Internet connection.My guess is that it checks the internet (somewhere) and figures out the relevant channels for your transmitter.