Did you update the ROM once you get a new replacement from the vendor?
Well, if the replacement is still faulty then you have the right to demand a fully functional replacement...you should check with your vendor
what do you mean for "update the ROM"?
Did you mean replacing flash memory ROM chip inside router or updating firmware by flash ROM?
You see this is cambodia, vendor don't know how to replace ROM chips, even knew no quality ROM chips available besides rampant evil china faulty chips in the market,also TPLINK will not allow vendor or distributor in cambodia doing it by refusing refund the goods ...
in vendor shop, we did updating firware to the latest, tried 20 routers, all the same problem:once power , config setting lost...so they said once switch on the router , better not switch off again, but once in brown hours, restarting again have to reconfig