Nintendo Switch w/NOK 5G21 Gateway

It basically boils down to an infrastructure problem TMO needs to fix on the other side of the modem first, and then updating the modem's firmware to properly enable/allow port forwarding to work.

EDIT: forgive me for the length of this post... it is a bit of a sore spot in the community, for obvious reasons like what you are experiencing.

The TLDR--gaming and IoT devices were NOT considered when they cobbled this service together.  It is really only designed for some of the most casual of users out there.  Unfortunately, the marketing and even their own reps do not make this distinction up front.  You MIGHT be able to get around some issues IF you can use a VPN with what you are doing... but success is limited due to issues with how things are managed.

Their network is IPv6 only.  Way too many devices and applications are designed with IPv4 with port assignments in mind.  While you can still assign ports with v6 addresses, the bigger problem is the reliance on v4 addressing.  You can't just "send" v4 addresses over v6 networks--the packets have to be altered on both ends of the v6 network for that network to carry the data back and forth to another v4 client (ie: some games trying to communicate with it's server via UDP protocol and v4 addressing).

TMO opted for an implementation of XLAT464 to handle the dual stack scenario that does not work for the peer-to-peer communication that many of these devices/applications depend on to function properly. While it works to get mostly all "stateful" v4 communications back and forth (you request outbound TCPIP connections that are established/tracked so they can transmit back to you), the "stateless" ones are broken. 

These are the types of connections that are not tracked at all... often UDP and not TCPIP, or otherwise inbound and unsolicited (you did not open a connection to them first--they are trying to reach out to you directly). These typically need a routing rule to forward such inbound traffic to a specific device, be that filtering by specific ports (set manually or via UPnP feature) or a DMZ rule that forwards all untracked/unassigned traffic to a particular device.

In theory, we should be able to get away with a DMZ rule on their modem to get around it--but their 464 implementation breaks things because of how they are filtering/shaping traffic.  It is behaving more like a "public" free VPN, or Carrier Grade NAT.  These can cause the public IP address to actually be used for multiple private users, so there is no 1 to 1 public address that can be paired to your modem or router's private IP in the usual fashion that would allow those peer communications to work properly. 

Communications MUST be initiated from your end first, and then the other end has to follow specific rules to reach back to you through that same connection for it to make sure it gets back to you properly.

Some have managed to get around it somewhat with a paid VPN service... but to get it work for things like game consoles it will require a VPN to run on your own router, which may narrow (or even void) your options considerably depending on specifics of your router.

And then there is the issue of the extra encapsulation for their 464 translation layer.  They have to use more space in the packet headers for their encapsulation, which reduces how much user data can go in each packet.  Instead of the more common 1500 byte client side MTU that leaves a 1460 byte MSS for user data, things get reduced to a 1420 MTU for the client, leaving only 1380 bytes for user data.  Some VPN's reduce this down to 1320 or less by default to avoid potential issues with their encapsulation--but not all of them.  So some are having issues getting VPN's to work properly... and not all allow the user to override the MTU or MSS values to fix it.

Basically... a LOT of people are getting hosed because TMO didn't have a clue of how people more often use their internet these days.  They are set up more for the extremely casual user... at best, a Netflix streamer and social media user.  Avid gamers certainly were NOT a consideration for this product... Heck, even the more casual gamer that likes the odd FPS game can get screwed by this system.

/endrant

I can’t play my Nintendo switch online it says

”Error Code: 2618-0521
The server is operating normally.
The NAT traversal process may have failed.
Intenta nuevamente más tarde.
If the problem persists, your network conditions may not be suited to stable
online play.
(50006)” 

my connection test says my Nat Type is D. I don't know why all the sudden it's stop connecting online I've been playing online fine for 3wks. Hopefully this get fixed I paid for a year of Nintendo online play so if it not fixed I have to get another home Internet 

In other words, someone at T-Mobile needs to read this and fix it stat! LOL. Darn. That sucks. Well, looks like I'll be going back to my previous provider for now. It is what it is. 

So is that just it? 
 

If you have T-Mobile 5G internet. You can't play most games online with Nintendo switch?

I have to use my iPhone 12 hot spot to play switch online. Please explain this to me? T-mobile needs to get their engineers working with Nokia to engage these most basic of hardware features that are needed. 

I was having the same issue with my gateway/switch as well. What worked for me, was going into the GUI and renaming the bands (2.4 GHz and 5 GHz), to essentially "separate" them so I could connect to the 5 GHz band on my switch, which seems to have solved the connection problem.

Can confirm this is an issue using the Nokia gateway provided by T-mobile. I've been trying to get a switch connected but it will not no matter what I do.

This is an issue for me as well. Same gateway.

When I first got it, I noticed a few issues but it didn’t really bother me a lot:

• On Steam on PC, I would always get an error for my friends list saying it was not online, but I was still able to play games and I don’t do hardly any party chat so I didn’t really care.
• On the Xbox, UPnP was always an issue, but same thing as PC I don’t really do party chat and I could still hear people in-game so I didn’t really care.
• My Switch seemed to work perfectly fine.

After having it for several months:

• Steam friends list issues seem to be resolved. I no longer get the error and I can see that people are online.
• Xbox UPnP issue still persisted. Eventually I started having MAJOR issues with ping where no matter what I did it was always above 200ms. So basically online was completely unplayable at that point. This lasted about a week before eventually I just said screw it and I got rid of the Xbox.
• Switch network stopped working entirely for no apparent reason, even when I had it connected over ethernet. I got rid of the Switch.

Honestly I would have cancelled my T-Mobile service except for the fact that I'm moving within a year so I can't commit to a contract with another ISP. So I just got rid of my consoles instead and now I only do PC gaming. Hopefully that doesn't fail too in the mean time. I won't be using T-Mobile again after I move.

Lesson learned: Don’t use T-Mobile home internet if you care about gaming.

FullKounter wrote:

I was having the same issue with my gateway/switch as well. What worked for me, was going into the GUI and renaming the bands (2.4 GHz and 5 GHz), to essentially "separate" them so I could connect to the 5 GHz band on my switch, which seems to have solved the connection problem.

How were you able to rename the bands? I have no idea what I'm doing here. We moved very far away from my family and I'm trying to help my son be able to connect with my little brothers for gaming on the switch. NAT type D here with the internet and A on their end. I don't get any of this it's way above my understanding. I'm on the Tmobile internet app trying to figure out the rename to see if it helps.

D-ocons wrote:

So is that just it? 
 

If you have T-Mobile 5G internet. You can't play most games online with Nintendo switch?

 

I just found this on another forum and it changed my NAT type from D to B on the switch. I'm waiting for my brothers to wake up and see if it'll actually connect this time. I'll update if it works but in the meantime this is what I found and followed.