MacOS – How to disable captive.apple.com

If you have a couple of computers kicking around to test AirDrop on, you can open a terminal on each machine and enter something like 'ifconfig -a' which will list all your networking interface cards. I'm not near a Mac or Unix box to show, but what you will see is a network interface that might be called say "en0" (Ethernet0) which is a physycal interface (may be wifi, or cabled) and a further one called "en0:0" which is a logical interface that piggybacks on top of the physycal interface. In this way you can run multiple virtual interfaces using just one physical one, and this is how AirDrop works. It is possible to manually create these interfaces yourself, and "multihome" your mac by having one interface say on a 192.168 address, and the other on say a 172.16 address, thus allowing it to talk to 2 networks at a time. It was always relatively straightforward on cabled interfaces, but I am not sure how tricky it would be (from a hardware support viewpoint) with wireless connections, but it's clearly possible in some way. See this question and answer for more details, but in short you need to be familiar with such terminal commands as ifconfig, netstat, route etc. Use the Airdrop network to access a computer?

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