Port 319
In live entertainment systems, port 319 is used by PTP (IEEE 1588).
udp/319
PTP (IEEE 1588) — PTP event messages (Sync, Delay_Req, Pdelay_Req, Pdelay_Resp)
IEEE 1588 Precision Time Protocol distributes a common clock across an ethernet network to sub-microsecond accuracy by timestamping messages in both directions. It is the timing foundation under AES67, Dante, RAVENNA, ST 2110 and AVB, and when it is unhappy all of them fail at once.
Check it from the command line
npx showstack port 319
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If you know something else uses port 319, tell us. Adding it is one file.