@Instegone 

First off let me say I do not have an AX110000.

Settings for a router will vary based on the network design and devices attached to it.

What works for me may not work for you.

Some points I use and have seen from others:

• Do not use Smart Connect so you have more control over the network.
• Use QoS only if needed and if you do, do not make all top priority
• In most cases, use a feature only if it is needed.
• If all of your devices do not support a feature, you do not ned to use it.
• Use default and auto settings unless specific settings are needed
• You are only as fast as your slowest link. A Cat 5 cable will limit you to 100 as can the network driver in your PC. 
• Setup and use IPv6
• Use quality Ethernet cables Cat 5E or better. If getting new ones get Cat 6 or better.
• Be sure your modem has many up and down channels as that has an overall speed effect.
• Use Ethernet connections over WIFI when possible
• Keep your network simple in design. The more parts, the more issues you will encounter.
• Router placement matters. Central location, higher tends to be better, keep it in the open so it does not overheat,...
• In most cases, keep the firmware up to date
• Use the highest WIFI security your devices support.
• Do not hide the SSID as it does not increase your security but can hinder connection to devices.
• When making changes to the router, make backups so you can always return to a known point. Power cycle/restart the router after a change as some changes happen only after a power cycle or restart. Make only one or very few changes and test so you know the full effects of the change. I like to back up, make my change, restart or power cycle the router, and use it long enough to ensure all is okay depending on the change, sometimes for days.