VPN: CISCO Anyconnect
VPN Error Message: Connection attempt has timed out. Please verify Internet connectivity.
Note: I'm able to connect to the vpn if I use my cellphone as a hotspot or if I set my SBG7580-AC device to bridge mode and connect my spare laptop (which I set as a hotspot).
Very annoying issue.
Nothing unusual there, it just sounds like you've got some interference to your SBG7580's WiFi signals on the 2.4 or 5 GHz bands. A VPN will not tolerate any uncorrectable data packet error, it just drops the connection and tells you to reconnect.
When you use your cellphone as a hotspot, you are using your cell service provider's network and the WiFi radio of your phone. When your modem is in bridged mode and you use a second computer as the WiFi hot spot, you are also NOT using your SBG7580's WiFi.
What is the common factor here: The VPN works when you are NOT using the modem's WiFi. How do I fix that? Reprogram your modem's WiFi operating channels to match what is selected in the spare laptop computer. Don't pick a channel used by any of your neighbors. If you run your smartphone on home WiFi in order to save on data usage charges, you'll have to delete the WiFi data and then re-enter.