A second connection that actually fails over

[Amanhasnoname]

A phone hotspot as the backup plan only counts if it kicks in without anybody touching it. The usual version is: cable drops, the platform goes grey, and two minutes later someone is hunting through Wi-Fi menus with an open position. Two minutes is long.

How Windows chooses a route is by interface metric. Keep the hotspot connected all the time, but give the wired connection a lower metric so it wins while it works. When the cable dies, traffic shifts to the hotspot within seconds. Existing connections to the broker will still drop, since the source IP changes, so the platform has to reconnect. That usually takes a few seconds, not zero.

Expect the mobile route to be slower: 40 to 80 ms is common, with more jitter, and some carriers use CGNAT, which occasionally annoys platforms on reconnect. Data usage for quotes alone is modest, but a VPS or screen sharing on the same link changes that picture. A router with dual WAN, with the second link on a different carrier or technology, handles the switch itself and is the cleaner option.

Whatever gets built, test it. Pull the cable during a demo session with a pending order and see how long the platform needs to be back and quoting.

Dual-WAN router or a tethered phone: which one has actually survived a real outage?