VIAVI TestCenter: Why does my 800G port have light off, temp low and not forming a link
Knowledge Base - FAQ
VIAVI TestCenter: Why does my 800G port have light off, temp low and not forming a link
Check Register Address 26 and change it to 0, if not already.
The port may be running in low power mode, setting it to 0 is the setting for max power.
After setting Register Address 26 to 0, port worked as expected and formed link.