You can find more background on the WLED website, too:
https://github.com/Aircoookie/WLED/wiki/UDP-Realtime-Control Hyperion You can now use WLED with the popular Ambilight software Hyperion. Just configure Hyperion to use an UDP device with protocol 0 on port 19446! The maximum number of LEDs supported in this mode is 490. (WLED 0.8.0 and lower: 341)(Bearbeitet)
Plus the rationale by WLED-Developer Aircoookie: Aircoookie Feb '20 Hi Maik, unfortunately the 490 LED is a hard limit. The reason is that the maximum amount of data that can be transmitted via a UDP frame at once is 1472 bytes (and we need 3 bytes data per LED). You could try to increase UDP_IN_MAXSIZE in wled07_notify.ino, maybe the 8266 (or at least ESP32) can handle larger UDP packets by reassembling the frames, but I wouldn’t count on it.
You could build your own WLED or live with the limitation....