Coincidentally this started happening not long after added a couple of new things. I plugged in a new Cisco SG300 managed switch and I plugged the gateway into a new APC UPS.
It was also a day of thunderstorms, but it seems to me I had it better protected in the UPS now.
The first thing that happened was that suddenly nothing could log into the wireless network. I kept getting errors that I couldn't connect. Not bad logins, just wouldn't connect. I reset the wireless on the gateway and that seemed to fix that. But I also noticed that I was getting timeouts on the gateway. I could only reach it maybe 50% of the time.
I ran some long ping tests from a hardwired computer and saw about 50% packet loss when pinging the gateway. I unplugged my new switch (it has L3 capabilities, so I thought maybe there was some routing problems going on), restarted the gateway, reset the broadband connection and it seemed better.
This morning I ran the ping tests again and got the same result (still have Cisco switch disconnected). Also having the same access issues. Obviously this is causing sporadic internet access problems. It also is impacting streaming services.
I just called to get a new gateway shipped out, but I wanted to see if anyone else has suddenly encountered an issue like this? Could be the box got hosed, but that just seems unlikely to me. I disabled HPNA (not using it) and IPv6 (also not using it) just in case, but that didn't have any effect that I could see.
Did you reset all components on the network ?? The CISCO switch may have had it's DHCP active and it would have caused problems with the DHCP server running in the NVG589. I had the same issue that you described when I first placed a Dell Managed switch on the network with DHCP active.
I would temporarily disable the wireless on the NVG589 and then power down every device connected to your network. Power up the NVG589 and once you get all green lights turn on the computer that you have hard wired to the NVG589 and test the connection. If the problems have been resolved turn on each device and test after each one.
If you want to add the CISCO SG300 switch add it before turning on you other devices. Verify that the CISCO SG300 gets assigned a proper IP address from the NVG89. (I use a static IP address in my managed switches, NAS and printers on my network that are outside the NVG589 DHCP range.) Once you get the CISCO SG300 working move the hardwired computer connection to the CISCO SG300 and test your connection.