Just like everyone else who owns these it seems, I am having major issues with HS105 units, two brand new ones. Setup goes smoothly and the unit works. Almost exactly 5 minutes after plugging in the unit, it makes another DHCP request to my router despite already having an IP from when I plugged it in and working. At the same time it makes this new DHCP request (and router does respond normally with same IP it already had) the unit goes into local only control mode. So if I disconnect from WiFi, no control, and of course Alexa control doesn't work since device no longer has connection to Internet it seems.
After about 10 minutes of being in this local only mode, the unit drops WiFi all together, then rejoins WiFi and works again with remote access/control. But, almost exactly 5 minutes later AGAIN, it no longer can connect to internet and local control only it is. This cycle repeats over and over. Once it goes to local only, if I unplug the unit and plug it back in, I get remote control back without waiting the 10 minutes, but sure enough 5 minutes later it is gone again. It's almost exactly 5 minutes everytime so something in the plug is causing internet connections to timeout to TP Link servers.
I have tried changing DNS servers on WiFi network to 220.127.116.11, set WiFi to 20Mhz width and manual channel 1. I have factory reset the unit after doing all of this. And I am on firmware 1.1.3 with hardware v3. I even tried placing an explicit allow rule in my firewall to the unit to make sure absolutely no traffic to internet is being blocked somehow. None of this helped, both units continue to lose internet, but retain local only every 5 minutes on the dot.
Hoping someone has found a fix to this while waiting for TP Link to fix their issue with plug's internet access.