Unassigned by IANA; the plausible listener is VNC display :59.
5959 has no IANA service name; the registry covers it only as part of the Unassigned 5915-5962 range. Under the RFB 5900+display rule it is display :59. Anything else answering here is a private application that simply picked a free high port.
Do not expose
An unidentified listener in the VNC block should not be reachable from untrusted networks; confirm what owns it locally before opening anything.
$ nmap -Pn -sV -p 5959 TARGETSeen this on your network? Beige Box scans your Wi-Fi and shows every open port on every device — and its Ports tool links straight back here.
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Corrections or a missing port? Reply @rimrocksystems.