How Can I Understand Common Wifi No Access

Understanding Internet Addressing

When connecting to the Internet, you are assigned a unique Public IPv4 or IPv6 address, such as 193.111.104.66 or 2000:fe1b:d335:ff6c:9933:6300:cc77:d85b. Verifying this information can be done at https://test-ipv6.com/. However, sharing and communicating these addresses can be challenging, especially when dealing with MAC addresses like 32:6f:2e:03:8c:e6, and doesn’t provide historical data about previous issues.

Navigating the World Wide Web

When accessing a website like https://cole.co, your computer first contacts a DNS server to transform the host part (cole) and the Top Level Domain (co) of the URL into an IP address, such as 214.4.227.194. All web requests from your computer and browser include the type, as seen in the example:
Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko

The Significance of Default Gateways

Your default gateway is typically assigned automatically via DHCP, and commonly ends in .1 or .254, depending on the scope size, such as 192.0.0.192. This gateway serves as the point where your computer forwards all its traffic for routing. For IPv6 troubleshooting, a comprehensive guide can be found at how-to-fix-ipv6-connectivity/, and specific commands for Mac or Linux include:

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  192.0.0.192    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:f4b9:13:f557:6524%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): {214.222.178.103, 2.161.181.112}
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 32:6f:2e:03:8c:e6
  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 3b:4d:4a:d3:60:d9
}

Resolving Issues with Wired and Wireless Connections

When it comes to sending data to your router, you may utilize either a wired or wireless (Wi-Fi) medium at the physical and data layer.

How to Address Problems on Apple’s macOS / OSX

Regardless of the version of OSX/macOS you are using - whether it’s 10.12.5, 11.1.4, or 12.1.8 - there are various troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that are embracing remote work and the Work From Anywhere (WFA) concept.

Utilizing Built-in Scripts for Assistance

One tool that proves to be very helpful on OSX/macOS is sudo wdutil info, which provides a dump of current wireless related settings to the CLI, and can be configured to generate specific logs for troubleshooting. Furthermore, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only point-in-time in relation to wireless, similar to 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 &. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose, which will provide a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to point Finder to the path. However, be aware of the file sizes, which are approximately 300MB more or less.

Possibly Helpful Videos

Video	Title	Channel
	WIDS/WIPS / Reseller FAQ WLPC Wireless LAN Weekly EP 14	Wireless LAN Professionals
	Automated Root Cause Analysis in Wireless Networks Karan Gupta	Wireless LAN Professionals
	The Importance of Broadcast/Multicast Filtering in Wi-Fi HD Arjan Koopen WLPC EU Budapest 2016	Wireless LAN Professionals
	Apples to Apples: An Analysis of the Effects of mDNS Traffic Bryan Ward WLPC Phoenix 2023	Wireless LAN Professionals
	Wi Fi Issues in the Wild Gopinath K.N. WLPC Phoenix 2018	Wireless LAN Professionals

Table 1.0 - Video Help