I have an RS6000 server running AIX and on occasion all users are logged out of the server "connection closed by foreign host" is the error message. Normally a user can press enter and get a Login prompt, but they get the message "connection refused" and then the users can wait a minute or so and then log back in. What's causing this? Is there a setting for tcp/ip that needs to be adjusted? Could the router or hub be causing this?

Doubtful that the router or hub is causing this problem only because the message received is coming from the host.

It sounds like the host service is bombing out and then restarting ( you did not mention which service but since everyone can connect again in a few minutes, it must be restarted by the server - look in /etc/inetd.conf possibly)

am not sure but I think the users are getting kicked of because of the default timeout value set in either the /etc/services file or /etc/inetd.conf file (not sure which one exactly. i'd have to check up on the files

anyway, in either one of the files listed above you might have to edit the lines pertaining to tcp/ip to contain a -t parameter. you include the -t to specify the amount of time users are allowed on a certain host before they are logged out. example

tcp nowait yadiyadiya yadiya -t1800
(not exactly what it would look like in your files but am just being too lazy to check up on the proper format)

this line specifies users are given 30 minutes to do whatever they goto do.

i mean, you can play around using this concept and things should work out