Hi, and thanks for your suggestion.
But as mentioned in the original post, I've already tried many older FW.
"I've tried to:
Revert firmware to 4.30, 4.20, 4.00, 3.90, 3.60 and 3.40"

Even tried to re-upgrade and re-downgrade. No difference, still get cannot calculate route on all searches.

Any other ideas? :-)