add ns https://my.freenom.com/knowledgebase.php?action=displayarticle&id=3
There are some online suggestions about Freenom and DNS problems
( if problems are confirmed with some tools! ) to force Freenom DB to be updated/refreshed
the first is to go into Freenom settings
and return to their default NS and wait 6h
then put the custom NS back and wait at least 30min-24h
the other is to delete the domain from their system and then add it again
after that config. custom NS and then wait at least 30min-24h