Cannot connect D-link AC1200 wireless card to AT&T cable-modem.
 

I have a Slackware64 14.2 computer with the KDE desktop. I have installed a D-Link AC1200 Dual Band PCIe card, "11AC Wi-Fi", dual band 2.4GHz/5.0Ghz. This connects just fine with an ASUS RT-N66U dual band wireless router. It will NOT connect to an AT&T 5268AC cable-modem with wireless. However, a USB dongle of currently unknown manufacture when installed in that same machine connects to the AT&T just fine, indicating to me that the passphrase and security mode are correct (same PW used on both the USB and D-Link) . WPA2-PSK Security is used in all cases.

When trying to connect with the D-link, it thinks for a while, then reverts back to asking for the passphrase. As I said, this card did work with the ASUS wireless router, but not with the AT&T.

I have no idea where to begin looking for the problem. Individually, all the pieces work, just not D-link to AT&T.

The hard part was getting the card to work.

Do you have any phone or tablet that you can use to connect to ATT wirelessly?

My guess is that you are out of leases or some setting in the ATT modem is stopping this.

By the way, ATT modems sometimes do not allow traffic between wireless and hardwired systems and no obvious way to get it to work. I have that same setup and use a double nat to lest Asus router on lan and modem on wan. I prefer the Asus anyway to use usb as backup to phone tethered.

jefro: Yes, there are other devices, including 2 other computers and an Android smartphone connected to this ATT. Nothing hardwired. The ASUS I mentioned is located at a completely different site, not in the same place with the ATT.

I noticed, however, that the D-Link card is seen by the ATT, but on the 5 GHz band whereas the other devices are all on the 2.5 GHz band. Perhaps a) the ATT needs more configuring for the 5 GHz band to work? Or b) I need to get the D-Link onto the 2.5 GHz band. I don't suppose you'd know how to do (b) on KDE?

Didn't realize there were two sites.

Maybe see if you can assign two names to the frequencies. I like to use for example asus and asus5 so I can find out what I am looking at.

Could be that the 5ghz was never tested before or set in guest mode or maybe even no ssid.

Yes, good idea. I'm sure the 5GHz has never been tried. It has the same SSID as the 2.5GHz band, but I know on my ASUS I had to set a pass[word|phrase] separately. If that's also true for the AT&T I'm sure it's never been done. Will try various things and post back.