Alright, here’s the deal:  I had recent cabline line with 90VAC on the line - yep, shocked at one point, so I checked.  My original modem was squealing, assumed it was dead.  Neighbors had internet.  Modem was an older Cisco DPC3010, so nearly a decade old, but still fast enough for me.  Assuming the dead original modem, not aware of the voltage on the line, I went and bought another modem so I could finish my work projects that were past due.  Plug new modem in instantly squeals at me and all lights solid - no change since then.  This was not the SBG8300 model.  So now two dead modems.  I’m an electrical engineer doing power system and control system designs. At one point earlier in career I was going for my Cisco CCNA; I decided to change careers and didn’t need to continue certification, but am not a complete novice when it comes to IT type stuff.

Several calls with xfinity, and they have tech come out and see voltage, works on line, and requests new line be buried and to have other tech work on main trunk line.  Main trunk line “fixed,” presumeably, as there isn’t 90VAC on it any longer.  I get about 3 VAC on it now, not sure if that is correct, but fast forwarding into the ordeal the line is functional with working equipment…

So, at this point, I believe I have two modems killed by Xfinity because of over voltage.  I work with tech support and eventually by this SBG8300 (yes used, but seller said worked fine, but went to fiber, and would take back if couldn’t get to work).  I’d like to get this one working.  So I try to provision through APP, and it wouldn’t see the modem.  Talk to tech support and they see it and I assume provision it, as the only feedback I got was that that they could see it was active.  Here’s the SBG8300 part, now that the background is set.

With the SBG8300, I could play with IP address and gateway settings on my laptop’s port, and I could connect to it - DHCP did NOT want to work.  So with manual settings, I could actually get to google, perform speed tests, go to ebay to auctions and things I’ve never loaded; I KNOW there is internet, BUT…  If I connect an iphone to the modem it shows no internet.  My laptop would show the network connection has no internet (even though I could do the things described directly above), AND my corporate VPN acted like there was no internet.  I tried factory resetting the modem and appeared to give the same results.

Does anyone have any thoughts on this?  Why would it work, but not?