Thanks very much for your response, FurryNutz. Problem solved.
You’re on the money. The IP address is not 192.168.0.50, rather it’s 192.168.1.50, even though the former is described as the default value in the D-Link literature. Not sure why D-Link customer assistance told me to change it back a year or so ago, but shame on me for not writing it down.
Based upon your suggestion, I set about to learn more about the Network and Sharing Center. As a result, this is what I did:
1. Disconnect the 2540 from the Internet.
2. Connect the PC by wire to the 2540.
3. Connect the 1522 by wire to the 2540.
4. Steps 1, 2, and 3 are the normal configuration, with everything powered.
5. Open the Network and Sharing Center on the PC.
6. Click on “Public Network"
7. Select “Home Network”.
8. Cancel the “Share with other home computers running Windows 7” window.
9. Click on “see full map”.
10. Hover the mouse over the icon of the 1522.
11. The Ipv4 address and the MAC address briefly appear. Copy the IP address.
12. Click on the icon of the 1522.
13. The login screen for the 1522 appears.
14. Log into the 1522 and obtain information, including the passphrase.
15. Return to the “Network and Sharing center” and reset the network location to “Public”.
16. Reconnect the 2540 to the Internet.
Again, thanks for the help.