Sorry it took so long for an update (been painting the new house)...

The problem definitely seems limited to a very few routers. Based on the excellent feedback I will be doing some more troubleshooting later tonight and tomorrow.

After browsing the Intel article (and I do have an Intel-based Mac) ... I think that's the issue right there. I did upgrade the firmware for the router to the latest version and have all of the Mac updates. The laptop is so new that I always had the latest update (I think) ... although I'll try updates again tonight.

Thanks for the help! I'll report back.
-Chris