Mavlink mode

By default WFB-NG encapsulates one source UDP packet into one WiFi packet. But mavlink packets are very small (usually less than 100 bytes) and send them in separate packets produces too much overhead. So for mavlink packets there is default setting [common] mavlink_agg_timeout = 0.1 which will aggragate mavlink packets while they less than radio_mtu but no longer than 100ms.