A few days ago, I found that several devices which should have been activated by a program that runs at sunset had not been activated. The ISY994 log indicated that the expected commands were sent at sunset and there was no indication of a problem in the ISY error log. When I started Admin Control panel, the only indication of a problem was a message which said that that a particular Insteon Bulb was not communicating. When I sent on/off commands to the devices, some of them responded, but the above Insteon bulb and several others did not. Some of the devices that did not respond were also linked to buttons on a RemoteLinc 2 2342-2 and they _did_ respond when the appropriate buttons were pressed. Then I attempted to reboot the ISY994 by issuing Configuration:System:Reboot from Admin Console. After allowing several minutes for the boot to complete I tried again to send commands to the devices from Admin Console, but the result was the same as before. Next day, I did a hard reset on ISY994 (button on front panel), but this had no effect on the problem. Then I did a hard reset on 2413s PLM. At this point, all devices responded to commands from admin console but the Insteon bulb that originally had a problem was still unreachable. Then I moved the bad Insteon bulb to another location, but it made no difference. Then I replaced the bad Insteon bulb with a new one. At this point, the new Insteon bulb and all other devices were reachable and Admin Console reported no errors. Later in the same day, Admin Console reported that an ApplianceLinc 2456s which had been OK before was not communicating. The ApplianceLinc was linked to a button on the RemoteLinc 2 mentioned above and it was responsive to this button. Moving ApplianceLinc to a different location had no effect. Then I cycled power to ApplianceLinc, but this had no effect. Then I unlinked Appliance from ISY994 and re-linked it, but this had no effect.
I have tried to re-enroll both failed devices (Bulb and 2456s) have been unsuccessful. Based on this post, my working assumption is that my 2413s PLM is on the way out and I plan to replace it. But it seems odd that two unrelated devices would apparently die within 24 hours while the PLM was acting up. Is it possible that an unhealthy PLM could actually cause damage to other insteon devices on the network?