NAT type determines how your connection handles inbound traffic and peer-to-peer sessions. Strict or double NAT can block multiplayer connectivity. Support teams check NAT status to identify CGNAT, port mapping issues, or router configuration problems before escalation.
What NAT Type Means
NAT (Network Address Translation) controls how devices inside your home network communicate with the public internet. Gaming platforms classify NAT into three types:
- Open NAT — Inbound and outbound connections allowed
- Moderate NAT — Some inbound restrictions
- Strict NAT — Most inbound connections blocked
NAT type affects:
- Peer-to-peer connectivity
- Voice chat
- Party matchmaking
- Hosting ability
NAT type does not directly change latency, but it affects connection reliability.
Why Support Asks About NAT Type
When diagnosing multiplayer issues, support needs to determine whether:
- The problem is routing-based
- The issue is peer-to-peer connectivity
- Inbound ports are blocked
- CGNAT is restricting traffic
- Double NAT is present
NAT status helps classify the fault before it enters the ticket lifecycle. See lifecycle context: What Happens After You Log a Fibre Ticket?
NAT Type Comparison
| NAT Type | Inbound Traffic | Peer-to-Peer Connectivity | Likely Cause |
|---|---|---|---|
| Open | Allowed | Full connectivity | Public IP / correct port mapping |
| Moderate | Partially restricted | Limited matchmaking | Router firewall rules |
| Strict | Blocked | Frequent connection failures | Double NAT / CGNAT / firewall |
Strict NAT often causes: unable to join parties, matchmaking errors, and voice chat failure. It does not usually indicate a fibre line fault.
Common Causes of Strict NAT
There are three primary causes of Strict NAT on residential fibre:
Double NAT
- Occurs when both the ISP router and the customer router perform NAT.
- Inbound traffic must pass through two translation layers, which often results in Strict NAT.
CGNAT (Carrier-Grade NAT)
- Due to IPv4 scarcity, many residential fibre services use CGNAT.
- Under CGNAT: multiple customers share one public IPv4 address, inbound port mapping is restricted, and hosting or peer-to-peer connections may fail.
- CGNAT does not indicate a fault. It is an address allocation model.
Disabled UPnP or Manual Port Blocking
- UPnP (Universal Plug and Play) allows devices to request port mappings automatically.
- If UPnP is disabled or firewall rules are restrictive, NAT type may degrade to Moderate or Strict.
Diagnostic Decision Flow
Identify NAT Type on Console or PC
- Check network settings: Open / Moderate / Strict.
- If Open — NAT is not the issue. If Moderate or Strict — continue.
Confirm Double NAT
- Is there more than one router in the network?
- Is the ISP device in router mode instead of bridge mode?
- Double NAT must be resolved before escalation.
Determine CGNAT Status
- If the public IP differs from the WAN IP shown in the router, or inbound connections are consistently blocked, CGNAT may be active.
- This may require ISP-side IP allocation change, not FNO escalation.
Eliminate Local Firewall Restrictions
- Verify UPnP is enabled, no restrictive firewall policies are active, and no manual incorrect port forwarding exists.
- If NAT remains Strict after validation, support can investigate IP assignment.
Key Term: CGNAT
A system where multiple customers share a single public IPv4 address. It conserves address space but restricts inbound connections, which can impact multiplayer gaming and NAT classification.
Why NAT Type Is a Support Variable
NAT type helps support determine:
- Whether the issue is connectivity vs physical line fault
- Whether escalation to FNO is irrelevant
- Whether IP configuration adjustment is required
- Whether router configuration needs correction
Strict NAT does not justify FNO escalation. It is not an access-layer failure.
South African Context
In South Africa:
- IPv4 scarcity drives CGNAT adoption
- Residential fibre often defaults to shared IP pools
- Public IP allocation may be optional
Support must distinguish between physical fibre outage, ISP authentication issue, and NAT configuration limitation. NAT classification prevents unnecessary escalation in the open-access model.
When NAT Requires ISP Intervention
ISP-side changes may be required if:
- CGNAT prevents required inbound traffic
- Static public IP is requested
- Authentication profile is misassigned
These are ISP-layer adjustments, not FNO faults.
Common Misconceptions
Clarifying what NAT type does and does not indicate:
- Strict NAT does not mean your fibre is broken
- Strict NAT does not increase latency
- NAT type does not indicate packet loss
- Escalation to FNO will not fix NAT classification
NAT is a routing and address translation configuration issue.