what's 4addr , is that a package I need to install?
For a sparse short packetloss test you want to see:
a) more or less constant delay (in your case ~64ms )
b) a low jitter (in your case 2.5 ms)
c) (next to zero) zero packet loss (packet loss under load is OK, as that is how the loaded router signals the flows to slow down, but on an unloaded link (and the packet loss should not be a significant load) packet loss should be zero or really really small).
I understand your situation, it is just that wireless is not as robust and reliable as a wired link... That said with little load on a WiFi bridge there should not be packet loss unless you have an RF noise issue which badly affects the wireless link.