Qnet forgets

I have two QNX 6.3.0 systems that are always on line and running Qnet.
It seems like after a period of not trying to access the other, like
overnight, they seem to forget that the other one exists.

If I do:
ls /net
they will each show themselves.

If I do:
ls /net/{other_system}
then the other system shows up. Also, then, both systems WILL show up in

Can this be fixed?