On 11/15/17 11:48, Juan R. de Silva wrote:
My ISP replaced my old modem with the new one. I changed my WiFi Authentication key and the name of the WiFi network. Then I made Network Manager to "forget" my old WiFi. Network Manager finds my new WiFi but I cannot connect to it. When "Authentication Key is required" dialog pops up and the key is entered,j Connect button remains grayed out/disabled. Thus there is no way to get through but pressing Cancel button. I'm running Debian Stretch. Could somebody help. It's quite urgent now.
I assume your ISP provided a combination "gateway" device, rather than just a modem (which would require you to provide a firewall/router and/or WiFi access point) (?).
I assume you are using a laptop (?). What desktop environment are you using (Gnome, KDE, Xfce, etc.)?
I assume the laptop WiFi interface was working correctly with the previous ISP device (?).
Try deleting all wireless entries in your "Network Manager", rebooting, and making a fresh wireless connection.
If all else fails, does your laptop have an Ethernet port? Do you have a long Ethernet cable? (You might need a crossover cable if your laptop or gateway has 10 Mbps or 100 Mbps Ethernet ports.) Power down, connect the cable, boot, and use your network manager to configure (if the laptop does not connect automatically).
David