To confirm that this issue was not a problem with my laptop/WiFi network adapter I managed to get hold of a very old laptop using the 2.4GHz band only, and now I can see that this is seeing issues communicating to some of the 5GHz devices. I also installed "Ping IP" on an Android tablet using the 2.4GHz band, again I have issues pinging some of the 5GHz devices. My new laptop on the 5GHz band has no issues communicating to 5GHz devices, but cannot see any 2.4GHz devices when the problem occurs.
The only way for me to get all 2.4GHz and 5GHz devices to see each other continually/without issues is to reboot regularly as tbrig1 has suggested earlier.
One thing I noticed, Amazon Echo Dots do not reply to pings at all on both 2.4/5 GHz, this is the only device in the house that doesn't reply.
The only way for me to get all 2.4GHz and 5GHz devices to see each other continually/without issues is to reboot regularly as tbrig1 has suggested earlier.
One thing I noticed, Amazon Echo Dots do not reply to pings at all on both 2.4/5 GHz, this is the only device in the house that doesn't reply.