X6 AC3200 WiFi intermittent

My router is about 6 months old and the best I could buy short of commercial variety. I had problems at first with the firmware update and almost sent it back. It started working but I have never had consistent connectivity to Wi-Fi. It’s beyond 90 days and I fear I wasted 400 plus dollars. I use 4 cameras and 4 Amazon echo devises none of which give me reliable Wi-Fi. I can reset all and get connected, but the connections will drop. I bought an extender (AC 1900) thinking it might help. None are greater than 60 feet from the router anyway. Rebooting helps for the short term, sometimes. Any suggestions? Thanks