Question about AVM FRITZ!Box 5490 Fiber

Directly no. Salt will provide you with a 10gbit router, and you must use that. (This FB doesn't provide such speed. But if you need additional functionality, you can attach it to salt router (transforming it just as modem/gateway). I'm using various FB as secondary routers (and WiFi repeater, and phone gateway). Note but not on salt, there I just use salt (first time that I do not use a secondary and better router)

You need to check with your broadband provider☝🏾 Not all provider’s broadband will be compatible. However, they could create a bridge via their standard router etc. It did not work with my provider Flashcable, we tried🤦🏻