Any have same problems with RB411AH showing wrong voltage I cheeked with instrument adapter is showing 24.00V plus I have 20m FTP cable from AC to RB411AH

Where are you measuring voltage ? At the adapter or in the router board ?

To be sure I would measure at the board itself.

Routerboards with older designs had problems with voltage reading. It was dependant on temperature. If you search forum you could find other people, lately there where one person who even showed 2 graphs that showed how voltage fluctuated along with temperature reading.

Newer design boards have different electrical layout and different logic behind measuring chain and they are not suffering from this issue.