I can't answer any firmware question.
However I do suggest the usual default setup noted in the CNET Networking Forum. Some routers don't work well with hidden SSID, MAC filters but the details are not in your opening post so not much can be offered yet besides the old "try it our way" routine.
I know how frustrating this issue is, hope there is something we can try.
This is an ongoing problem and I am wondering if a firmware update is called for. We have had the router for some time and to the best of my knowledge nothing has been done to fix the problem except the old "unplug for 10 seconds" routine.
There are now four users on the home network with multiple devices.
Can anyone advise me as to how to approach this problem?