hi geddy and techman, thanks for your responses!
concerning the lights "Error light and Memory light blinking simultaneously:"
this is true BUT the power and rx lights are still on as well. still thinking network problem?
"Boot up sequence: Power, RX&TX, momentary blink of Memory/RX and TX, and then Power only"
mine never gets to power only, my final light configuration is power, rx on solid, memory and error flashing
"router" = eero on 192.168.4 network. att bgw210 on 192.168.1 network. the isy does not show up on either router.
"Do you have ISY Portal activated for this device" no
"It's always best to set a DHCP reservation on your router" dhcp reservations are set up on both routers and i checked that no other devices are using the address specified for the isy
"If you have a PLM make sure that it is powered on and connected before you power on the ISY" done and i can see the lights on the plm below the rj45 port blink when i power up the isy
"It's possible that putting the network into the PLM port and the PLM into the network port (on a ISY994)" the ports are wired properly
techman, i've confirmed all the points within your post
any possibility it's a sd card/corrupted file system issue?? thanks again guys!