I had very strange issue recently. I have two embedded computers (vp7 and vp9). Vp9 machine have intel i82544 network adapter , on the vp7 machine - pcnet32.
Qnx version 6.4.0.
On the vp9 machine I don’t lost udp packets, but on vp7 I regulary lost packets.
If I invoke “pidin -p io-pkt-v4-hc mem” I see , that pcnet32 network driver (devn-pcnet.so) is work via devnp-shim.so. But on vp9 machine network adapter (devnp-i82544.so) work without devnp-shim.so. May be this is a core of the problem??? And how I can play with network adapter options???