Possibly somebody walked or moved near the net or a ball rolled near the net. When Boomer is expecting a serve, it looks very closely at the net and can see thru the net all the way to the service line on the other side of the court. If any ball or person (or leaf) enters this sensitive area, Boomer will think the ball hit the net and call a “net”. On very windy days, the net itself may move enough to trigger this bad call. If so, the “net sensing option” can be disabled using the setup menu. If the net sensing is disabled, you can now cheat by hitting the ball hard into the net with no penalty and keep serving until you get an “ace”. Let your conscience be your guide. If you really want to beat Boomer, you can unplug it and claim a forfeit. Or set the level down low enough that you can win every point. Boomer has no ego and doesn’t care.