How to set 4G for SIM card?

[ArjenU]

Due to severe problems after updating OS, I needed to go back to factory settings. Now I to get the one sim-card on which I have a 4G-subscription to provide me with the 4G connection. However, I get the screen as in attached screen shot 1, below.
Can anyone tell me how to get the 4G functioning again? (Settings at provider are ok, as far as I can see)

Could it be related to the fact that my sim-card does not have its phone number related to it? Screenshot 2 shows “number unknown”. How can I connect the card to the number I use?

Screenshot 1

Screenshot 2

[paulakreuzer]

Here is a neat collection of settings you should check:

No internet access via mobile data after update to Android 6.0

You have to check multiple locations in the “Settings” menu: Settings → Wireless & Neworks → SIM cards → Preferred SIM for → Cellular Data Settings → Wireless & Networks → Data usage → [select SIM] → Cellular data (Should only affect Internet speed and not whether you get an Internet connection at all) Settings → Wireless & Networks → More → Cellular networks → [select SIM card] → Preferred network type (If this is greyed out, put the other SIM card to 2G before.) Settings → Wireless & Network…

[ArjenU]

Item 3 did the work: needed to set the other sim to 2g. Now it seems to work.
Thanks a lot!