I apologise if this initial post is light on diagnostic detail, but I had to come into the office and do some real work.
I've been running an SG565 at home for probably 4 years (a kind gift from the guys at the former Secure Computing UK outfit, before they became part of McAfee) on my cable broadband service. Setup and configuration was a doddle - simply connect port B of the SG to the Ethernet port on the supplied cable modem and configure port B to use DHCP to obtain an address. This has worked flawlessly until today.
My ISP has been rolling out a nationwide infrastructure upgrade in the UK which has resulted in a trebling of my connection speed. However, in order to facilitate this they had to send me a new device as my old cable modem didn't support the new speeds. My new "SuperHub" (as it is called) arrived today. It is one of these consolidated modem/router/firewall/wireless devices (and it is actually made by Netgrear). I connected it in place of my old cable modem and went through the prescribed activation process. This was all done using a laptop connected directly to the SuperHub and everything was hunky-dory. An online speed test showed I was getting my new speed and I was happy with the results.
Fortunately the ISP has recognised the more technically inclined who have their own infrastructure and don't need all of the additional functionality over and above the physical connectivity to the broadband service. So, accessing the device's GUI, I located the option to revert to basic 'cable modem' mode and it went through an obligatory re-boot. Once it had re-booted and with my laptop still connected I ran the ipconfig /release & ipconfig /renew commands and this resulted in my laptop now having a public IP address, rather than the private address it had previously been issued with.
OK, I thought; time to connect everything back up again. Re-booting the cable device again, I then also logged into my SG and re-booted that also. After a short while I was able to access the SG internally, but when I looked at the Network Configuration screen it claimed that port B was still "waiting" for its IP address to be assigned. Approximately 5 minutes later the entire cluster of LEDs on the front panel started flashing in unison.
For the time being I have put the external device back into "Hub" mode and the SG is perfectly happy about that - it has been able to get a 192.168 DHCP address from the hub, but this currently means that I have a double NAT environment to contend with (which will interfer with my IPSec VPN tunnels), but at least it works.
I will take another look when I get home to see if I can extract anything of use from the SG's logs. But if anyone can think of what may have happened, and why, I'd be very grateful to hear from them.
Many thanks in advance.