The Tools > Other Settings in Asuswrt-Merlin firmware is a menu not found in the stock Asuswrt firmware. It enables us to tweak some network settings to the router, which most of the time we can just keep them at default value.
Traffic history is a small database storing information required by the Traffic Analyzer. By default it is stored in RAM, which will be lost after the router is restarted.
You can set the traffic history location to NVRAM to preserve the data after router restart, and set the frequency whereby the database will be copied from RAM to NVRAM. Note that the NVRAM in the router has a finite times of read/write cycle. It is advisable to set the save frequency not to be too frequent to prolong the wear-and-tear of the NVRAM.
A better way is to save it to custom location, which can be a mounted USB storage device.
If your ISP billing cycle is not on the first day of the month, you can change the default starting day of monthly cycle from the default 1 to the first day of your billing cycle. This will enable you to have better view of your monthly traffic based on your billing cycle.
Asus routers such as the RT-AC86U have a physical button for you to turn off all its LED lights. This is a feature for you to conceal the router, particularly at night or in dark condition. Asuswrt-Merlin provides you the software option to turn off the LED lights by enabling Stealth Mode in miscellaneous options. In fact, you can further tweak your router to automatically turn off the LED lights during certain time, and make them function as normal during other period of time. You can click here to learn more about scheduled LED control.
New firmware version check will alert you when you login to the router and there is new Asuswrt-Merlin firmware available. You will still need to manually download the firmware after getting the alert, and perform the update accordingly. You are given the option not to check for beta firmware releases.
For TCP/IP settings, just keep the default values unless you have certain network application, such as VoIP, that need the tweaking. TCP connections limit is in quantity. All the timeout values on the screen are in number of seconds.
In IPv4, Address Resolution Protocol (ARP) is used to find out and associate the Media Access Control (MAC) address of a network interface with its IP address. It was done by a broadcast in the Layer 2. In IPv6, ARP is replaced by Neighbour Solicitation. By default, IPv6 neighbour solicitation broadcast is allowed by the internal firewall of the router, and Asuswrt-Merlin allows you to instruct the internal firewall to drop such broadcast, if it bothered you.
The Asuswrt firmware has a program called WANduck, which handles tasks related to your Internet (WAN) connections. WANduck is "inherited" in Asuswrt-Merlin firmware.
By default, WANduck will keep on sending DNS queries every few seconds to check if your WAN link is connected or not. You can disable this in the advanced tweaks and hacks settings. It is advisable not to change the default setting, unless you are clear about your reason to disable it.
Asusnat tunnel is a special NAT tunnel built-in to enable access to the router from the WAN side, even under NAT network. It is used by certain features, and the Asus Router mobile app. If you are paranoid about this kind of tunnel, you are given the option to disable it.
The Web Proxy Auto-Discovery (WPAD) protocol is a technology which aids a web browser in automatically detecting the location of a Proxy Auto Config (PAC) file using DNS or DHCP. The PAC file contains information of web proxy server.
By default, the DHCP server in the router will send empty WPAD with a carriage return to the requester. If this behavior causes problem, you can disable the sending of carriage return in empty WPAD.