Coection failed when I try to update my cell phone firmware

I have Android cell phone (Lenovo A7000 Plus) and I get inteet from my router through Wifi, all the applications and Google play work normally but when I try to check for firmware update I get coection error message

I tried my cell phone on other routers and the update check work normal so I think my router has a problem. My router is NetGear DGN3500 so please advise what I should do to be able to update my firmware from my router Wifi coection ?