What are the steps to scan the nmap IPv6 addresses?
How can I use nmap to scan a range of IPv6 addresses?
Recently, I saw a blog with details of IPv6 scanning, Since 2002, Nmap has offered IPv6 support for its most popular features. In particular, ping scanning (TCP-only), connect scanning, and version detection all support IPv6. The command syntax is the same as usual except that you also add the -6 option. Of course, you must use IPv6 syntax if you specify an address rather than a hostname. An address might look like 3ffe:7501:4819:2000:210:f3ff:fe03:14d0, so hostnames are recommended.
I would assume that the range you are trying to scan i fe80:0000:0000:0000:0000:0000:0000:0000/112 which is the last 16 bits (the last section) of the address. That range includes 65,536 IPv6 addresses, probably all of which are going to time out when scanned. It will probably take most of a day (86,400 seconds - close enough to 65,536 at one second per timeout on average) just to ping that range to determine whether the machines are up or not.
But such small ranges are rarely seen. ISPs are often handing customers a /64 range each, (and it seems this is what you have) meaning that the customer has 18,446,744,073,709,551,616 individual nmap IPv6 addresses. Scanning a single customer like this would take years.
There are discovery protocols that exist to allow you to find the exact IP address you need rather than scanning the entire range and these might be a better place to start.
There are some existing answers here that may still help: Which tool (apart from nmap) can I use to scan a range of IPv6 addresses?