"WCDMA only" option is not available under preferred network type on Xiaomi Redmi Android Phone

On some Android phones, "WCDMA only (read 3g)" is not specifically selectable under "preferred network type ". This is also the case on Xiaomi Redmi abdroid phones. Only the following options are available :
1. Prefer LTE (4G)
2. Prefer 3G
3. 2G Only

The above options are fine except for the word "prefer",

which will not force the phone to stay on 3g/4g.

On reasearching online, here is a workaround found which can be tried.

1. Go to dialer and type *#*#4636#*#*
2. Select the phone information1 (sim 1) or phone information2 (sim 2)
3. Scroll down and look look for Set preferred network type
4.Tap and select "WCDMA only" from the options.
5.Tap back key to exit.

That's it.

Source: miui forum