I have changed nothing on my SBG8300 to have caused this problem.  For several years I have used this home modem to connect to my company VPN and then log into my company's factory firewalls to access their network(s).  I have been using the company issued Cisco AnyConnect VPN software.  For the past month, when working from home,  I am not able to access the firewalls and the browser reports that the address cannot be found.  On infrequent occasion I have connected to a firewall but there is no rhyme or reason for why it worked.  Restarting the modem does not help.  My internet provider (Xfinity) tech support remotely examined it and didn’t know what the problem was so she suggested I get a new one (LOL, she gave up).  I can access the firewalls using my cell phone hotspot or another location that provides internet, but not through my modem.  At one point today I tried disabling the modem internal firewall but that did not help.  When I re-enabled the modem firewall and restarted the modem, then restarted the AnyConnect app, I got a message prompt from Cisco AnyConnect saying “The VPN connection to the selected secure gateway requires a routable IPv4 physical adapter address.  Please move to an IPv4 network and retry the connection or select a different secure gateway.”  I restarted the AnyConnect program and the next time it did not give me that message and, oddly, I was able to connect to all available firewalls.  I restarted AnyConnect and tried again and none of the firewalls were found.  Any gurus out there that could give advice on this would be appreciated!