New UI Input, moving between input fields on mobile

I need need to create a few different input field objects on the screen, each is limited to one letter.
When the user changes the letter in the first one the next one immediatly becomes active and the cursor is moved there and so on between all of the input fields. The code i’m using now is:

if(nextLetter != null)

nextLetter being the next input field gameobject.
This works great on pc but dosent work at all on mobile, The keyboard open for the first field but when the value is changed it just closes and I need to choose each field seperatly.

Any help will be appreciated!
Thank you

Help anyone?