I've been having tons of issues with the HSxxx devices staying connected to the local network.  Symptoms are:

• Devices are randomly unreachable, from random hosts on the network.  I.e., one phone might see the device, but another wouldn't.

I have traced this issue down to WMM APSD.  If you are experiencing this issue, in your wireless settings:

• If you have APSD or "Advanced Power Management/Advanced Power Save Delivery/WiFi Power Saving" or similar, disable it.  Reboot your router, and (just to be sure) reboot your plugs.
  • This change may use battery power somewhat more quickly for any phones or tablets connected to the wifi.
• If you do not have an APSD setting, try disabling WMM (or "WiFi MultiMedia" or possibly "Prioritize multimedia" or something similar.
  • This may cost you wifi call connection quality, use more phone or tablet battery energy, and possibly decrease video quality for some devices on the network.

Once this setting is changed, your plugs and other devices should stop disappearing from the network (at least after a router reboot).  Give it a day or so to make sure the problem is really cleared up.  If this didn't help, turn the WMM or APSD setting back on.

Note to devs:  Hopefully this will give you an angle on resolving the issue that has been plagueing some homes for hs100, hs200, and hs300.