The various Ethernet ports on your router can serve different purposes, depending on the model. Thankfully, it's not hard to discern what they're for.
Your router's USB port hides features most people never find.
Compare dual-band and tri-band routers, exploring 2.4 GHz vs. 5 GHz bands, Wi-Fi 7 6 GHz options, network congestion handling ...
Your router can do a lot more than you think it can, including some functions you might have thought were only possible using desktop or phone apps.
Your old router shouldn't be destined for the recycling bin. You can repurpose it to extend your current network and much more.