I've got a weird problem here, my new Ubuntu install can access the internet, ping other computers on the wireless LAN, ping servers outside the network (ie: google.com), and ssh into itself using its network ip ( and also The problem is that no other devices on the network can see, ping, or ssh into Ubuntu unless I ping the other computer first from Ubuntu. After I ping the second or third computer from Ubuntu, I have maybe 60 seconds to initiate some sort of network traffic from the second computer to Ubuntu, or else it disappears again. If I ssh into Ubuntu during that time, I'll remain connected until I choose to disconnect, but then a minute or so later, I can't talk to Ubuntu at all. Even weirder, if I have Computer A pinging Ubuntu indefinitely, and Computer B pinging Ubuntu indefinitely, at first neither one will get any response. If I ping Computer A from Ubuntu, then Computer A will instantly start getting a response, but Computer B will not get anything. Visa versa works too, pinging Computer B from Ubuntu results in Computer B seeing Ubuntu, but Computer A still doesn't.

I've got Ubuntu set up with DHCP, but the router has a reservation for set up for Ubuntu's MAC address. Also, ifconfig says that Ubuntu's IP is throughout all my experiments, so I know I'm still pinging the right IP.

Running nmap on Ubuntu , it can see any device on the network. I don't have another Linux machine to test to see if any other computer can see Ubuntu with nmap, but running Fing (a network mapper similar to nmap) on my Android tablet finds all the other devices, except Ubuntu.

I'd really like to know what's making it so that Ubuntu has to initiate communication with another computer before that computer and only that computer can talk to it at all.