I'm streaming UDP data through this router. The 5 Ghz radio is shutdown. The 2.4 Ghz radio's antennas are set to diversity, and maximum power.
If I remove the first antenna (left-most, facing the router), the number of missed message packets skyrockets. Once I put the antenna on again, things settle down. This doesn't happen with the other 2 antennas.
Well if the router is still configured for diversity, removing an antenna is not the thing to do. You can change this with "antenna transmit left" and "Antenna receive left" on the radio interface for example if you only kept the left antenna.
Left/right is determined when you look at the side of the router where the antennas are. so facing the antennas.
The right one is always "primary" which means it's the default one where router sends/receive on diversity. The left antenna only takes over when it's providing better signal.