Cisco 2513 Ether/Token Ring Remote Router, Dual WAN, 8MB Flash, 16MB DRAM
Cisco 2500 Series Router 2503 ISDN, 2x serial + free AUI eth,works! original box | eBay
Cisco 2500 series - Wikipedia
My grandfather gave me a Cisco 2500 series router and it looks like it predates Ethernet. How can I get this working? What are all these ports, what signals do they use,