No registration and no documented service; the 19090-19110 range is empty at IANA.
IANA assigns nothing between 19090 and 19110, 19101 included, and Nmap records the port as unknown while still scanning it by default on frequency grounds. Applications sometimes number an internal service 19101 as part of a self-chosen block, but there is no convention to point at. An open 19101 is an unattributed service.
Expose with care
Nothing about the number justifies exposure. Find the owning process and judge that.
$ sudo lsof -nP -iTCP:19101 -sTCP:LISTENSeen 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.