Packets dropping and massive ping spikes at regular second intervals
In my experience regular-interval (not random) WiFi drop-outs have been caused by:

1) WiFi access point SSID conflicts between 2.4Ghz and 5Ghz bands. Modern WAPs (WiFi access points) often have 2 different radios and can be set to use either different SSIDs for each radio, or the same SSID for both bands. If your WAP is 2.4Ghz/5Ghz capable and uses the same SSID for both bands, be sure the authentication settings and keys (WPA2 Personal + wifi passwords) are exactly the same for both bands.

If they are not the same your Mac may connect to only one of them, but periodically try to "upgrade" to the other SSID in hopes of getting higher speed. (E.g. your mac may be joining the 2.4Ghz network and periodically attempting to move to the 5Ghz network, but failing to join the 5Ghz network because it has different security settings/password from the 2.4Ghz. The "attempted join" lasts a few seconds, but fails -- and during this time your ping stops responding.

2) DHCP-related conflicts between identical SSID 2.4Ghz and 5Ghz networks. See this post: WAN connectivity failure every 5 minutes on Technicolor router

3) Uncommon, but occasionally a buggy external USB device can cause Wifi network problems at the driver level. Some kind of strange incompatibility between the hub's particular implementation of USB &amp; Mac OS X's USB stack. Be sure to disconnect all external USB peripherals when testing.



In your particular case it would be useful to know more about your network setup. What kind of WiFi access point is it? How long have you had it and has it been reliable up to this point?  How many other devices are connected to it? Do they experience any problems?  How close are you to sources of WiFi interference (mainly other Wifi networks, in urban areas these days it is common to see 30+ SSIDs pop up from neighbors access points. Even suburban areas sometimes. Also in apartment complexes.