Many routers today use "Airtime Fairness" or "Wi-Fi Multi-Media (WMM)"
These settings are there to make sure higher bandwidth devices, like phones and streaming boxes are able to get maximum speed, even if an older computer might be on the network. This works by limiting the speed and access time of the older devices. It unfortunately can also cause low bandwidth devices like LIFX lights to show as non-responsive in the app and in some cases even prevent setup of a device, that uses similar small amounts of data to communicate on the network.
This can be addressed, especially on your 2.4Ghz network, which should not be hosting streaming devices and other computers that can take advantage of the maximum speed provided by your internet connection. To adjust these settings, please login to your wireless router settings and navigate to advanced settings and DISABLE Airtime Fairness and/or WMM. This will create the best environment for your LIFX lights.
Other routers may call this QOS or Optimize AMPDU (A MPDU). For purposes of managing connections with multiple LIFX, check for all these types of settings on your router, and ensure they are OFF or DISABLED.
Asus RT-88U Example:
Make sure you disable WMM AMPSD and Disable Airtime Fairness for 2.4Ghz network
Nighthawk R7000 Example
Make sure WMM is disabled for the 2.4Ghz network