I need to change the Local IP Configuration on my TC8717T gateway. (This is at my employer's request, to solve a perceived problem on the other end of a VPN connection.)
I changed from 192.168.0 to 192.168.11.
After restarting the gateway, all devices in the house could connect to the gateway, but none of them had Internet access, whether via hard wire or Wi-Fi.
Any ideas why changing the IP address of the gateway would block access to the Internet?
Yes, there is a good reason. The local IP address of both the router and modem is preset in the rental gateway device programming. Change it back to 192.168.0.1 where it belongs, so that the router can find the modem and provide your computer with a data connection to the internet. For the future, remember: that address is on your local home network, it is NOT the public IP address to which the VPN connects.
If you must change the local address of your computer, you should change it to a static IP assignment of 192.168.0.11. And if your printer is wireless-only with no ethernet port, you'll need to assign it a static IP address too - use last segment 99. This process is detailed in section 7.2 of the user manual, on page 63.