Having thoroughly read Michael Murphy's guide to routers, I am still unsure what to do. Essentially I want a robust router without CLI, and don't really need it to have wifi.

Our current setup is an Airport Extreme and  2 Airport Expresses (in bridge mode) handling AP duty connected via Ethernet back to the Pace Gateway (with Wifi turned off) . I can tell via Netspot app that we have excellent WiFi coverage. I have had multiple wired APs due to old house with lathe and plaster being very unfriendly towards wifi. We have been having lots of slowdowns over the last 6 months where things take an age to start loading, although once videos are streaming technology, we rarely if ever have a problem with buffering. So I started to think that the Pace Gateway just could handle all the different requests, and that was the  problem. So I ordered a Spark Huawei HG659b, thinking that a modern Spark router would solve it. But that was even worse - devices stopped being able to even find the internet at all. Then I looked at total connected devices in our house, and it is hovering up around 30! So even though i was using the Huawei with Wifi turned off, it felt like the Huawei couldnt handle the number of devices and was dropping them. I subsequently understand that the HG659B has a 32 device limit. With the Pace Gateway back in the circuit, devices don't get dropped off anymore, but I am back to the same issue that we have frequent slowdown at initiating web page connections, , an age to load things, app startup on phones etc.

Of course it could be that the Airports are the issue, but as I say - Wifi throughout is really strong, and I remain suspicious that the Pace Gateway is at Fault. I know I couldn't handle a router with a CLI. Although I don't need a router with Wifi, all the non-wifi ones seem very technical. Would one of either the Asus AC68U, Netgear R7000 or Ubiquiti Amplifi devices solve the issues I describe? I would aim to put them in the circuit with Wifi disabled, because I am primarily looking for strong routing ability, but as I say, I am trying to avoid a device that requires me to use a CLI, and I can't seem to find a high quality non-wifi router that doesn't have a CLI.

Thanks for any helpful advice. I will probably be told to ditch the Airports I know, but I also use them as Airplay devices, and have a housewide Dual band single SSID setup, , loads of Apple devices, Apple TVs etc so keen to keep if possible!