How To Understand Common Wifi Connectivity

Understanding Internet Addressing

When connecting to the Internet, you are assigned a unique public IPv4 or IPv6 address, such as 232.159.111.63 or 2000:c6d5:e525:e347:718b:80dd:7fcc:ba91, respectively. You can verify your address on https://test-ipv6.com/. However, translating and communicating these addresses, or even complex MAC addresses like ee:e1:07:fb:4f:87, can be error-prone, especially without access to historical data.

Navigating the Web

Accessing a web page, such as https://jerde.io, involves initially contacting a DNS server to translate the URL’s host (jerde) and Top Level Domain (.io) into an IP address, like 178.48.209.103. Furthermore, your computer and browser transmit their type with all web requests, such as:

Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36

Understanding Default Gateways

The default gateway is typically an automatically assigned address via DHCP, such as 10.29.226.176 (usually ending in .1 or .254, depending on the scope size). This is where your computer forwards all its traffic for routing. For IPv6, a comprehensive guide on how to fix connectivity issues is available at /blog/how-to-fix-ipv6-connectivity/. Additionally, you can verify on Mac or Linux with the following command:

ifconfig

IPv4 Routes and the Host IPv4 Route Table (inc. VPN)

netstat -rn -f inet | egrep -i "default|0/1|128.0/1"

0/1      172.18.12.193  UGScg  utun3
default  10.29.226.176    UGScg  en0
128.0/1  172.18.12.193  UGSc   utun3

Note: We are not just looking for the default but also for any VPN that overrides the public v4 address space.

IPv6 Routes and the Host IPv6 Route Table (inc. VPN)

netstat -rn -f inet6 | egrep -i "default|2000::/3"

If you have IPv6 active the above should return at least one route (as per below) via a known interface such as “en0 " on a Mac.

default   fe80:24aa:7401:1e4f:afdf%en0  UGcg   en0
default   fe80::%utun0                   UGcIg  utun0
default   fe80::%utun1                   UGcIg  utun1
default   fe80::%utun2                   UGcIg  utun2
2000::/3  utun3                          USc    utun3

Note: We are not just looking for the default but also for any VPN that overrides the public v6 address space.

Debugging DHCP for both IPv4 and IPv6

To get a look at the low level DHCP configuration (Mac/Linux):

ipconfig getpacket en0

...
domain_name_server (ip_mult): {14.8.2.47, 153.2.67.153}
end (none):
...

So, in the above we are not getting IPv6 DNS servers from the DHCPv4 reply but…

ipconfig getv6packet en0

DHCPv6 REPLY (7) Transaction ID 0x80940b Length 76
Options[4] = {
  CLIENTID (1) Length 14: DUID LLT HW 1 Time 668691856 Addr ee:e1:07:fb:4f:87
  DNS_SERVERS (23) Length 32: 2606:4700:4700::1111, 2001:4860:4860::8844
  DOMAIN_LIST (24) Length 0:  Invalid
  SERVERID (2) Length 10: DUID LL HW 1 Addr e7:b9:11:1c:22:cc
}

Solutions for Dealing with Wired and Wireless Connections

When it comes to transferring data to your router, you have the option of using either a wired or wireless (Wi-Fi) medium at the physical and data layer.

Tips and Techniques for Apple macOS / OSX Users

Regardless of the version of OSX/macOS you have, whether it’s 10.11.2, 11.0.3, or 12.2.1, there are various tools available for troubleshooting. While manual actions and scripts offer some help, they do not provide a series of related values over time. This is where automated remote troubleshooting shines, particularly for teams that are embracing remote work and Work From Anywhere (WFA).

Useful Built-in Scripts

One highly useful tool on OSX/macOS is “sudo wdutil info,” which provides a dump of the current wireless settings to the CLI and can be configured to generate specific troubleshooting logs. Additionally, the “sysdiagnose” tool can be used to generate a wide range of logs, although much of it is only relevant to wireless at a specific point in time, much like wdutil.

To run sysdiagnose in the background and write logs to “/var/tmp/.tar.gz,” you can use the command “sudo nohup /usr/bin/sysdiagnose -u &.” For an interactive (although minimal interaction) experience, you can use “sudo /usr/bin/sysdiagnose,” which will give a privacy warning. If not run in the background, it should open Finder in the correct location, or you can navigate to “/var/tmp” using Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB.

Possibly Helpful Videos

Video	Title	Channel
	Next Generation Troubleshooting with Meraki Wireless Devin Barger WLPC Prague 2018	Wireless LAN Professionals
	The Importance of Broadcast/Multicast Filtering in Wi-Fi HD Arjan Koopen WLPC EU Budapest 2016	Wireless LAN Professionals
	Do You Have A Wired or Wireless Problem	Wireless LAN Professionals
	Wi Fi Issues in the Wild Gopinath K.N. WLPC Phoenix 2018	Wireless LAN Professionals
	Apples to Apples: An Analysis of the Effects of mDNS Traffic Bryan Ward WLPC Phoenix 2023	Wireless LAN Professionals