What Is Starlink’s CGNAT Limitation?
Starlink’s CGNAT limitation is a technical cap on how many simultaneous TCP and UDP internet sessions one connection can maintain before older sessions are dropped to make room for new ones. Starlink’s Residential and Roam plans sit behind Carrier-grade Network Address Translation (CGNAT), a system that lets many customers share a limited pool of IPv4 addresses. On these plans, Starlink sets a hard ceiling of 1,200 concurrent sessions. Once that 1,200-session limit is reached, any new session forces the oldest one to close, which can look like a sudden disconnection or app failure. According to Starlink’s support information, this can disrupt VoIP calls, video meetings, online games, and VPNs that use many parallel connections. The result is confusing: speed tests look fine, but certain activities keep dropping without warning.
Carrier-Grade NAT Explained in Plain English
Carrier-grade NAT, or CGNAT, is a large-scale version of the home NAT in your router. Because IPv4 addresses are scarce, providers cannot give every customer a unique public IPv4 address. CGNAT lets many subscribers share a single IPv4 address while keeping their traffic separate with internal mappings. The trade-off is control and capacity. CGNAT devices track every active session, and industry documentation encourages providers to cap those sessions so one user cannot consume too many resources. Starlink follows this pattern with its 1,200-session limit. Although Starlink also supports IPv6, IPv6 is not backward-compatible with IPv4, and many sites still lack IPv6 support, so IPv4 (and CGNAT) remain important. This mix of protocols means most people are fine most of the time, but heavy or real-time apps can hit the ceiling.
How Internet Session Limits Cause Drops and Lag
Internet session limits become visible when you run many connections at once. A “session” is any active TCP or UDP conversation—every video call, game connection, web tab, or VPN tunnel can spawn several sessions each. When Starlink’s CGNAT box reaches 1,200 active sessions for your line, it drops the oldest ones as new ones start. In practice, that can freeze a VoIP call mid-sentence, boot you from an online match, or disconnect a VPN while other devices appear fine. According to networking consultant Daryll Swer, most households will rarely hit 1,200 sessions because roughly 80% of typical Starlink traffic can use IPv6 instead of IPv4. Still, heavy multitasking, always-on smart home gear, torrenting, or multiple gamers and remote workers in one home can push you over the limit and trigger hard-to-diagnose Starlink connection drops.
Practical Ways to Avoid Starlink CGNAT Problems
You cannot change Starlink’s CGNAT design on Residential or Roam plans, but you can reduce how often you hit the 1,200-session ceiling. Start by limiting apps that open many connections: disable constant torrenting, lower the number of simultaneous downloads, and close unused browser tabs or cloud sync tools on idle PCs. For gaming and calls, avoid running large updates or other bandwidth-hungry software in the background. If you manage your own router, use QoS to prioritize VoIP, video calls, and gaming so that less critical traffic is more likely to be dropped first. Make sure your devices prefer IPv6 where available, which shifts load away from the CGNAT pool. If you still see unexplained Starlink connection drops during normal use, collect timestamps and app names—they will help Starlink support review your usage patterns and suggest plan or configuration changes.
When to Ask Starlink for a Static IP or Other Options
Some users need more predictable connectivity than CGNAT gives. Heavy VPN use, hosting services from home, or running busy multi-user networks can expose the Starlink CGNAT limitation. In those cases, open a support ticket and ask which options in your area provide a public or static IP, and whether those plans enforce different session policies. A static IP does not magically remove all limits, but it avoids CGNAT sharing and can give you more stable inbound connectivity and easier port forwarding. If a static-IP option is unavailable or unsuitable, ask support whether a different Starlink plan better fits high-concurrency workloads. In parallel, keep tuning your own network—segment guest devices, schedule large downloads, and monitor how many services run 24/7. With the right mix of plan choice and local hygiene, most users can keep Starlink CGNAT issues to a minimum.
