Sometimes reducing to basic connections can narrow down connectivity issues ...
*Try iLink connected directly to the HELIX ...
*Try iLink connected directly to the 999 ...
*Try 999 connected directly to the HELIX ...
If these work without issue - suspect the AS ETH 5XPG either not getting power or just being flaky ...
If any of the above also has issues - suspect a bad Ethernet cable ...
Rickie