Notes

1.As with troubleshooting any other connectivity issue, first verify the following:
Modem RF levels in spec
Firmware version is up-to-date
Firewall settings are set to optimal (Low)
Connectivity to Internet has been verified using non-VPN device (personal smartphone, etc.)
Note: Network Engineers have verified that port 443 does not get blocked. See the list of blocked Internet ports.
2.Comcast gateway devices' IP networks are defaulted with Gateway Address 10.0.0.1, which means the DHCP addresses available range from 10.0.0.2 to 10.0.0.254. Most Client VPN software that companies will give their teleworker employees will utilize a 192 DHCP "range." This means that, unless the router settings are manually changed, the customer will not be able to connect to the VPN. The customer should verify all settings and work with their IT to set up this connection. If needed, we can provide a few additional steps of guidance.
3.To update the Gateway Address, use the MSO Graphical User Interface following these steps:
Log in to MSO GUI using the POD
Navigate Gateway > Connection > Local IP Network
Change the Gateway Address to 192.168.0.1
The DHCP range will automatically update accordingly after selecting Save Changes
Note: This process may have the ability to temporarily disable connectivity to previously connected devices, so it is beneficial to verify that the affected devices can still surf. If not, disconnect and forget the network - then reconnect using the same credentials. The customer's devices should automatically be assigned with the proper 192 protocol.
4.Next, you may set up a reserved IP for the affected device:
Select Connected Devices
Locate the affected device, note the IP, select Edit
Check the Reserved IP radio button > Save
5.The customer can try doing a release/renew and DNS flush. For commands and instructions, see IP Address Release and Renew.
6.A simple way to verify is to send a ping specifying that port. (Provided the customer doesn't have a firewall.) The customer can test TCP ports by telnetting to the specific port.
Select Start, Control Panel, then Programs and Features (or Programs).
Select Turn Windows Features on or off.
Check the box for both Telnet Client and if available Telnet Server.
Select OK.
In a command window, type 'telnet [IP address][port number]', leaving out the brackets ([ ]).
7.A list of ports and blocked ports:
http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers
List of Internet Ports that are Blocked
8.Have the subscriber work with their company's IP support group for assistance. Anything else is beyond demarcation.