Model no.

[stephkane00]

Hi just got galaxy s21 plus  model no.sm-g996b/ds can u tell me if this is a uk model.still on oneui 3.i November update 

[ianbuk]

Yes, it's a UK model

[stephkane00]

Thanks can u tell why I'm still on oneui3 I'm on three network uk

[ironass]

What is the Samsung CSC code of your Galaxy S21+, (SM-G996B)? 

Go to... Settings > About phone > Software information > Service provider software version (See screenshot)

[stephkane00]

There u go

[Blessed4life]

Hi, try connecting your device to a computer with smart switch installed & see if you can update that way.
Or try going to a Samsung service store if possible.

[ironass]

You are on the stock Samsung, non-carrier branded, CSC code BTU.

Try @Blessed4life 's suggestion and try and update using the Samsung Smart Switch PC suite.

[Ziddy]

DON'T update to ONEUI4 yet.
Loads of issues.
My OK Google won't work, app crashes.. was fine before, wish I could downgrade