AC-3100 problems afther last firmware update

[KAwifi]

hi,

I have a ac-3100 and it work very well, si after de latest asus firmeware update, i have some connexion lost and i have to turn off wifi and turn on again to see the web page or app fonction like eBay. Yes, ebay or other apps tell lost connexion problème. How can a return to the previous firmware or if bette to use à Merlin firmware?

Thanks!!!