Undersea Cable Internet: How to Improve Reliability

Updated 15 November 2026 · Standard formula, shown below

If your internet connection relies on an undersea cable—whether you live on an island nation, a coastal region, or your ISP routes traffic through submarine lines—you may experience higher latency, occasional slowdowns, or complete outages when those cables are damaged or congested. This guide explains practical steps you can take to improve the reliability of your connection, from optimizing your home network to using alternative routing and backup options. You don’t need special technical skills, but a basic understanding of your router settings and ISP options helps.

What You’ll Need

Access to your router’s admin interface (usually via a web browser at an IP like 192.168.1.1 or 192.168.0.1)
Your ISP account credentials (for contacting support or changing plans)
Optional: A VPN service subscription (for routing around congested paths)
Optional: A secondary internet connection (mobile hotspot, satellite, or a different ISP) for failover

Step-by-Step

Identify the bottleneck. Run a speed test and a ping test to a server on the other side of the cable (e.g., if you’re in the Caribbean, test to a US East Coast server). If your ping is high (over 150 ms) or packet loss is noticeable, the undersea link is likely the issue. If your local speeds are low but ping is fine, the problem may be your home network.
Optimize your home network. Ensure your router is in a central location, away from walls and metal objects. Use wired Ethernet connections for critical devices (like a work computer or gaming console) instead of Wi-Fi. If you must use Wi-Fi, switch to the 5 GHz band if available, as it’s less congested than 2.4 GHz.
Adjust router settings for stability. Log into your router and change the DNS servers to a public, reliable option like Google DNS (8.8.8.8 and 8.8.4.4) or Cloudflare (1.1.1.1). This can reduce DNS resolution time and avoid ISP DNS outages. Also, disable any bandwidth-hogging features like automatic firmware updates during peak hours.
Use a VPN to route around congested paths. Sometimes undersea cables have multiple landing points, but your ISP may route you through a congested one. A VPN can force your traffic through a different path, often improving latency and reliability. Choose a VPN with servers in locations that make sense for your traffic (e.g., if you’re connecting to US servers, pick a VPN server on the US East Coast). Test with a free trial before committing.
Contact your ISP to check for alternative routing. Call your ISP and ask if they have multiple undersea cable providers or if they can route your traffic through a different landing station. Some ISPs have redundancy options for business customers. If you’re a residential customer, they may not offer this, but it’s worth asking.
Set up a failover connection. If your undersea cable is frequently out, consider a secondary internet source. A 4G/5G mobile hotspot can serve as a backup. Many routers support dual-WAN or USB tethering. Configure failover so that if the primary connection drops, traffic automatically switches to the backup. This won’t improve speed, but it keeps you online during outages.
Monitor cable status and plan around maintenance. Undersea cables are often repaired during scheduled maintenance windows. Check your ISP’s status page or websites like submarinecablemap.com to see if a cable near you is under maintenance. If you know a maintenance window is coming, plan large downloads or important video calls around it.
Consider a satellite internet backup. For critical needs, satellite internet (like Starlink or traditional geostationary services) can provide a completely different path that bypasses undersea cables. This is more expensive but offers true redundancy. For most home users, this is overkill, but for remote work or businesses, it might be worth it.

Common Mistakes

Assuming all slowdowns are cable-related. Before blaming the undersea cable, test your local network. A faulty router, old Wi-Fi, or a congested home network can cause similar symptoms.
Using a VPN that adds more latency. Some VPNs route your traffic through distant servers, making things worse. Always test the VPN’s ping and speed to your target server before relying on it.
Ignoring firmware updates. Outdated router firmware can cause instability. Keep your router updated, but schedule updates during off-peak hours.
Not checking if your ISP has multiple cable paths. Many ISPs have redundancy but don’t advertise it. A simple call could reveal you can be switched to a healthier route.

Tips

Use QoS (Quality of Service) settings. If your router supports it, prioritize traffic for video conferencing or VoIP to reduce jitter and packet loss.
Test with a wired connection. Wi-Fi introduces latency and packet loss. For critical tasks, always use Ethernet.
Keep a log of outages. Note when outages occur and how long they last. This helps your ISP diagnose patterns and may help you negotiate a better plan or credit.
Consider a local caching proxy. For frequently accessed content, a local cache (like a Raspberry Pi running Pi-hole) can reduce the amount of traffic that needs to cross the ocean.
Use a load-balancing router. If you have two connections (e.g., cable and mobile), a load-balancing router can distribute traffic across both, improving overall throughput and redundancy.

Troubleshooting

If you’ve followed the steps and still experience issues:

Check if the problem is widespread. Use websites like downdetector.com or your ISP’s status page to see if others are reporting issues. If it’s a regional outage, you may just have to wait.
Reboot your router and modem. This clears temporary glitches and re-establishes the connection to the ISP.
Test with a different device. If one device has issues but others don’t, the problem is local to that device (e.g., malware, outdated drivers).
Run a traceroute. Use the command tracert (Windows) or traceroute (Mac/Linux) to see where packets are dropped or delayed. If the issue is at an undersea cable segment, you’ll see high latency or timeouts at a specific hop. Share this with your ISP.
If all else fails, switch ISPs. If your current ISP consistently provides poor reliability due to undersea cable issues, another ISP might have a different cable landing or better redundancy. Compare options in your area.

Frequently Asked Questions

Can I do anything to prevent undersea cable outages?

No, undersea cable outages are caused by ship anchors, earthquakes, or other events beyond your control. You can only prepare for them with backups and redundancy.

Why is my ping so high even when the cable isn’t broken?

Undersea cables have a physical limit: light travels slower in fiber than in a vacuum. For a cable spanning 10,000 km, the minimum round-trip time is about 67 ms, plus routing overhead. If your ping is higher than expected, it may be due to congestion or inefficient routing.

Will a VPN always improve my connection?

No. A VPN can help if your ISP routes you through a congested path, but it can also add overhead and increase latency. Test multiple VPN servers to see if any improve your specific connection.

Is satellite internet a good backup for undersea cable?

It depends. Geostationary satellites have high latency (over 600 ms), which is fine for email but not for gaming or video calls. Low-earth-orbit satellites like Starlink have lower latency (around 20-40 ms) and can be a viable backup for many uses.

How do I know if my ISP uses undersea cables?

If you live on an island or a country with limited land connections, your international traffic almost certainly goes through undersea cables. You can check your traceroute to a foreign server—if the hops go through coastal cities and then undersea, that’s the cable.

What is the best way to monitor cable health?

Use a network monitoring tool like PingPlotter or SmokePing to continuously ping a server across the cable. This will show you when latency spikes or packet loss occurs, helping you correlate with known cable events.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.