Thanks fitzpatri8!
Yes, its a brand new unit and brand new PLM (2413s). I did test the PLM before I started and access point test was no problem (just did it again, no issues).
But I never reach step 2 in your post. When I click "Start Linking" I get this error message ("Discovering Nodes. Retry"). In fact at that point, even if I change tabs (e.g. to Program Details) I get that message. Even if I disconnect the PLM I get that message. I did try setting an INSTEON device to linking mode and same issue (no blinking on ISY, just the error message).
I factory reset the PLM (powered off for 30 seconds, held button down and powered up, released button after 10 seconds). To no avail.
Maybe relevant: Also the ISY admin console keeps asking me for password ("My Lighting authentication" box pops up) every 15-20 seconds. Since the password is already filled in, I just hit OK and it goes away... for 15 more seconds. But I know I am connected to the ISY and authenticated since I can see stuff like SD card status, NTP server I saved etc., just keeps losing the session for some reason. I switched from WiFi to an ethernet LAN connection just in case it was the WiFi but again, still has the annoying popup.
Any ideas?
Thanks in advance,
ML