Your console grades your home network like a bouncer: "Open", "Moderate" or "Strict". The grade is less about speed and more about who gets through the door.
The short answer
A NAT type is a console's label for how well other players can reach you through your router's network address translation (NAT). Xbox calls the classes Open, Moderate and Strict [3], PlayStation uses Type 1 to 3 [6], and the Nintendo Switch uses A to F [5]. The IETF describes the underlying behaviour differently, with separate mapping and filtering rules [1][2]. Our assessment: the label matters most for peer-to-peer games and party chat. A fast line with a Strict NAT can still mean longer matchmaking or fewer reachable players.
How it works
- What NAT does. Your router translates private addresses into the public address of your connection. For UDP, RFC 4787 defines how: a mapping behaviour (which public port an inside port gets) and a filtering behaviour (which outside packets are let in) [1].
- Mapping. There are three: Endpoint-Independent, Address-Dependent, and Address and Port-Dependent [1]. RFC 4787 says a NAT must have Endpoint-Independent Mapping, because otherwise NAT traversal methods fail and a UDP relay is needed [1].
- Filtering. Again three: Endpoint-Independent, Address-Dependent, and Address and Port-Dependent [1]. For application transparency, the RFC recommends Endpoint-Independent Filtering. For stricter filtering it recommends Address-Dependent Filtering [1]. The RFC notes that the mapping choice does not change security; filtering does [1].
- Discovery. RFC 5780, an Experimental RFC, describes how a STUN client can discover the behaviour of the NAT in front of it [2].
- The console labels. Microsoft's developer documentation defines Open as able to connect with any console, Moderate as able to connect with Moderate or Open consoles, and Strict as able to connect only with Open ones [3]. Nintendo's test page says the type ranges from A (best for peer-to-peer) to F (unable to complete peer-to-peer) [5]. Epic's PlayStation help describes Type 1 as connected directly to the internet, Type 2 as behind a router with some limited functions, and Type 3 as behind a router with limited connectivity [6]. Sony's own page was not retrievable, so that part rests on a game publisher's summary. None of these pages says which RFC behaviour each label stands for.
- What changes it. Automatic port sharing through UPnP or PCP, or a manual port forward on the router [4][7]. Both need an address that can be reached from the internet: AVM states that its router needs an IPv6 address or a public IPv4 address for automatic sharing [7], and a provider-side shared IPv4 address (carrier-grade NAT) blocks incoming IPv4 [8].
A practical example
Your Switch says NAT type D. First check the line, not the console: in a FRITZ!Box, the Online Monitor shows whether the router has a public IPv4 address or only a shared one [8]. If the address is public, enable automatic port sharing for the console, or forward the ports your game lists. For Xbox the published list includes UDP 3074 and 3544 and says forwarding happens on the router, not on the console [4]. Then run the console's test again [5]. Our inventory (as of 14 to 16 Oct 2026) lists a UniFi router and firewall; its NAT and port settings are not recorded, so we say nothing about them here.
Checklist
- Run the console's own connection test and note the label and the date [3][5][6].
- Check whether your router has a public IPv4 address [8].
- Use UPnP or PCP only if you accept that devices may open ports on their own [7].
- Otherwise forward the ports the game or console maker lists [4].
- Re-run the test after each change; change one thing at a time.
- Write the final setting into your network notes.