Hi  @Sunshine  thank you for your response!

Sorry for the delay, but this issue is with my girlfriend's router, so I have to be actually at her house to try to fix this. 

Yes, it is the Nintendo switch from the internet settings detects the connection with NAT type F. Both mine and hers, with the same router, have this problem. At my house for example, we don't have any issue (and if I remember correctly it should be a NAT type B or A, but I have a different type of connection)

Even with a sim from the same provider the problem remains, logging in directly from the phone. 

Let's say that all online features are not blocked, because if it has to go to the shop or watch youtube there are no problems, but if it has to connect to the internet to play multiplayer games the switch goes into error (saying that it could not connect to the servers)

The IP Type is 10.56....... / :: but it should be a private IP, in fact we wanted to see if it was possible to make a switch so that my girlfriend can fully enjoy the online services

Greetings
Filippo

  @OtterlyFil 

Hi,

If the router shows a private IP address (10.56.....) for its "Internet" connection, then there is no way to get NAT type B or A on the Nintendo Switch if it's connected to that router.

Hi @woozle , that's bad news for me :( 

Can i fix this issue in any way? Not even changing the router? 

  @OtterlyFil 

The IP address of the "Internet" connection is assigned by the mobile/cellular network provider. Changing the router won't make any difference.

Only the network provider themself could "fix" this. (i.e. assign a "public" IPv4 address instead of a private IPv4 address)

The issue of mobile network providers assigning private IPv4 addresses has become very common in recent years. Actually there are very few left that offer public IPv4 addresses and sometimes only on user's request.

Eventually IPv6 should solve such kind of issues one day, but the move to IPv6 has been rather slow.