Adding a mesh router behind an internet-provider router can leave two devices performing Network Address Translation. That arrangement is called double NAT. It deserves investigation when a specific application fails, but the presence of two routers does not by itself explain every slow connection.

Google notes that many people notice no performance effect from double NAT. Problems are more likely to arise with particular gaming, address-assignment or inbound-connection workflows. Write down the actual failed task before changing the network structure.

Draw the current path

Make a simple diagram from the provider connection to the first router, the second router and the affected device. Label the ports and which device supplies each Wi-Fi network. Identify where printers and other local resources connect, especially if the computer and printer use different routers.

Record each device's current mode and the existing internet connection requirements. Include services such as provider telephone or television equipment that may depend on the original gateway. This inventory gives the provider or installer enough context to advise on a supported change.

Choose the device whose role should change

Google's guidance for its Wi-Fi products describes bridging the upstream modem/router as one way to leave a single device performing NAT. Follow the provider's instructions for the actual equipment. Do not assume that disconnecting a combined modem/router is equivalent to removing a separate router.

There are product-specific limits on the other choice. Google documents bridge mode for a single Wi-Fi device, with restrictions that prevent using the primary device that way in its multi-device mesh. Another brand's access-point instructions are not automatically applicable.

Arrange a change window, preserve the original settings and identify the recovery route before switching modes. Afterwards, check the original failing task, local printing and any provider-dependent services. Keep the diagram with the final roles marked. Successful browsing is one check; it does not establish that every service survived the change.

References: Google double NAT guidance.