Can You Use Two Different Internet Service Providers With One Modem/Router?

The short answer is no, but let's delve deeper into the nuances of this question and explore some practical solutions.

Understanding IP Addresses

Do you own your IP addresses or utilize them from a carrier? If you own your own IP addresses, then it would be feasible to use them with multiple ISPs. However, if you rely on a carrier's IP addresses, you might run into a significant issue. Carriers generally do not advertise nor route each other's IP addresses, which means that you cannot count on accessing their network from another carrier. Typically, this would require an advanced configuration using Border Gateway Protocol (BGP). However, this is usually done by enterprises with specific needs.

The Setup is Tricky

Although the concept sounds straightforward, the setup can be quite complicated. It requires routing tables on your devices to make it functional. ISPs frequently employ this setup for redundancy purposes, allowing them to switch between connections seamlessly in case of a failure.

Multi-WAN Capable Hardware

There are hardware solutions designed specifically for this purpose. These devices often come with 'multi-WAN' capabilities and can handle load balancing. Simply searching for such hardware on Google will yield numerous options. One example is equipment that runs two or more ISP connections in a fallback configuration, where the secondary connection takes over if the primary one fails. There are also load-sharing configurations that distribute data traffic more or less equally, and there are bonded internet configurations where data is split at the packet level to be reassembled at the ISP end.

Practical Considerations and Limitations

Generally speaking, it is not feasible to use two different ISPs simultaneously with just one modem/router. Each ISP connection requires its own modem to convert the signal into a data stream, which then feeds into a separate router to manage the incoming data. Each router needs a switch to distribute the data to end users. This means that you would need two separate modems, two separate routers, and two separate switches to manage two distinct ISP connections.

However, there are enterprise-grade network devices that can be customized to run multiple ISP connections in a fallback or load-sharing configuration. For instance, these devices can switch seamlessly between primary and secondary connections or distribute data traffic more evenly. Some advanced configurations even allow for bonded service, where packets are split and reassembled at the ISP level.

Years ago, I experimented with a dual ISP setup, using ADSL from the phone company and PPoE from a local provider. I had two separate LANs and a couple of computers with dual network interfaces to bridge the two networks. While this setup was intriguing, it did not provide any real benefits in terms of improved internet performance or reliability.

Conclusion

While using two different ISPs with one modem/router is not straightforward and is typically beyond the scope of a typical home network, enterprise-grade solutions can offer more advanced capabilities. For most users, however, sticking with a single ISP or exploring multi-WAN capable hardware will be more practical.