请问 iPad1 People 3G/4G SIM, not getting 3G, only 2G ? ?

I have a Peoples 3G/4G prepaid plan and a iPad 1 3G+wifi model. I can't get the 3G connection, only 2G (on the top left corner, it shows E next to CMHK, not 3G or H symbol). I set APN to either peoples.net and cmhk, I still can't get 3G.

Been to the CMHK store twice, they said in the Settings>Cellular Data page, I should have a choice to use 3G option, but there is no such choice in the page.

Thank you.

I did try to use the same SIM in a 3G wifi modem and the screen did show 3G next to CMHK.