@Ian52 

If you look at the sticker label below the router, does it say (US) or (EU)?

@Tony 

i can take a photo of the sticker tomorrow, but it's EU, it was bought in store in croatia. 

actually it should still be under warranty , since it has 36months warranty period. 

anything to do to extend 2.4ghz to ch 12 and 13 (least used in my building)?

also extending 5ghz to more channels would help to fight congestion. 

thanks

@Ian52 

I just looked at the non US - english TP Link forum https://community.tp-link.com/en/home/forum/32?page=1 (note 'en' instead of 'us' in the link) and found others reporting the same issue. I did not follow the posts but you may be able to find better answers on that site for your specific router.