Unassigned by IANA, no known service — it is in Nmap's default scan list only because hosts answer there.
IANA lists 19801 inside the unassigned block 19791-19997, so no vendor has ever claimed it. Nmap's service table carries it with an open-frequency but the label 'unknown', which is why it lands in the default top-1000 TCP scan and shows up in reports. In practice anything listening here is a private application, a container port mapping, or a service someone moved off its normal port. Identify the listener before you assume anything about it.
Expose with care
The verdict belongs to whatever is actually bound here, not to the number. Fingerprint it first; an unidentified listener on a public IP is a finding, not a service.
$ nmap -Pn -sV -p 19801 --reason 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.