nmap --script smb-os-discovery 192.168.1.1

This runs Nmap's smb-os-discovery script, which connects to the SMB service and reads the operating system banner the server volunteers. It reveals whether 192.168.1.1 runs a Windows version, Samba on Linux, or a NAS appliance. SMB must be open for the script to work, and the answer is a hint, not a guarantee.