How to prevent the Mac from switching Wifi connections when at home

Update: It wasn't the VPN client causing this, but after lengthy troubleshooting (see comments) it turned out to be Skype, possibly due to UPnP related bugs.

Try disabling your Cisco AnyConnect(?) VPN client (if you're not sure how, open Activity Monitor, find a process named acvpnagent and quit it).

From your description, it may well be the case that the VPN client is either failing to establish a tunnel or taking a rather long to do so, either of which could cause the apparent loss of the default route you're describing (you can ping anything on your local network, but nothing past the router).

If disabling the above (and any other) VPN client doesn't resolve it, please add the results of:

• ifconfig (not just ifconfig en1 - there's an interface utun0 appearing in your log)
• netstat -rnfinet

... at each of these stages:

• immediately after connecting to your Wifi (while the network seems to be up)
• during the problem
• and after recovery

1. Do you have DHCP enabled? Your laptop might be loosing its connection to the router due to IP conflicts resulting from other devices on your network using the same IP address.
2. Try using different broadcast channels. I think the default Linksys channel is 6. I usually use 8 or 1.
3. How good is the signal strength? You might have to boost the antennas transmission signal.
4. Make sure someone like your neighbors are not running APs with the same SSID.
5. If you use signal encryption try using different key encryption WPA/WPA2-PSK(AES/TKIP).
6. and the obvious one, run software updates, just to make sure that there is no new firmware for the MacBook NIC.