E5570 adding a WWAN card but which one?

Before buying anything, open the system and ensure the antennas are present for the card.  If they're not, they cannot be retrofitted (unless you're willing to replace the display assembly with one having the antenna leads).

The next thing to ask is what card(s) your service provider supports.

Then go about choosing the card.  Rarely has Dell offered more than two card options, though each can have individual part numbers (which is what you listed).

Hiya, thanks for the reply. 

The antennas are present. It’s just the WWAN card that is missing.

you mention checking which cards my service provider supports? Could you elaborate on that a little? 

thanks

Not all providers use the same technology -- or support the same cards.  Particularly if you're in the US, some cards are locked to certain providers.  It may be different elsewhere, but you need a card that's compatible with your service provider's network and with the type of service (probably 4G or 5G) you have.

Ahhh I think I understand. 

Here in the UK, all SIM cards are locked to their providers. I have no concerns with SIM compatibility. Both 4G and 5G are available here (as well as 3G) but from what I can see, the WWAN cards operate on 4G and not 5G?

Still, just need to work out which WWAN card to get as there isn’t much (if any) info on the differences and/or advantages of the different part numbers.

Dell DW5811e thats what you need and connect the grey/black wire to the side says Main 

and you should be good.

Thanks Mike, but which DW5811E? I’ve found 6 variants so far