Because i didn’t make a backup. For next time’s reference:
connection: &p1usb accepter: tcp,10001 enable: on connector: serialdev,/dev/ttyUSB0,local,115200n81
Older ser2net, shipped with debian buster with ‘just’ a .conf file is easy:
10001:telnet:600:/dev/ttyUSB0:115200 8DATABITS NONE 1STOPBIT banner