How To Test Common Wifi Connectivity

Functioning of Internet Addressing

When using the Internet, you will receive a Public IPv4 address such as 11.222.208.210 or an IPv6 address like 2000:f7c7:1aa6:16:a862:91e9:ad36:96ae. The authenticity of these addresses can be verified at https://test-ipv6.com/. However, for those who are not well-versed in technology, communicating these addresses or even specifying MAC addresses like 64:95:9b:05:d1:92 can become prone to errors and significantly complex. Moreover, this method fails to provide any historical data, particularly from previous incidents.

Navigating the Internet

When attempting to visit a webpage such as https://upton-lakin.info, the first step involves accessing a DNS server for the conversion of the URL’s host portion (upton-lakin), in combination with the Top Level Domain (info), to an IP address such as 204.234.194.3. In every web request, your computer and browser disclose their type, for example,
Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)

Significance of Default Gateways

Usually configured automatically via DHCP, your default gateway is the address you receive, such as 192.0.0.7 (although it typically ends in .1 or .254, based on the scope size), and serves as the point where your computer dispatches all its traffic to be routed forward. A comprehensive guide on troubleshooting IPv6 is available at how-to-fix-ipv6-connectivity/, while Mac or Linux users can check with:

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  192.0.0.7    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:e974:bc66:759e:5338%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): {118.9.2.72, 190.65.162.29}
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 64:95:9b:05:d1:92
  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 b5:3b:0c:01:2f:e4
}

Fixing Connectivity Issues: Wired vs. Wireless

When it comes to transmitting data, you may be using either a wired or wireless (Wi-Fi) connection at the physical and data layer to send data to your router.

Tips for Troubleshooting on Apple Operating Systems

No matter which version of macOS or OSX you’re using - whether it’s 10.14.3, 11.5.5, or 12.3.8 - there are various tools available for troubleshooting. However, these manual actions and scripts don’t provide a set of correlated values over time. This is where automated remote troubleshooting becomes especially useful, particularly for teams who are working remotely or operating under a Work From Anywhere (WFA) model.

Using Built-in Scripts for Assistance

An extremely useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings to the Command Line Interface (CLI). It can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a comprehensive range of logs, although it primarily captures point-in-time data related to wireless, similar to wdutil.

Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (although there isn’t much interaction), you can use
sudo /usr/bin/sysdiagnose, which will provide 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. Note that the file sizes are typically around 300MB.

Possibly Helpful Videos

Video	Title	Channel
	Wireless Association & Authentication Pass-Fail Brian Long WLPC US Phoenix 2017	Wireless LAN Professionals
	The Importance of Broadcast/Multicast Filtering in Wi-Fi HD Arjan Koopen WLPC EU Budapest 2016	Wireless LAN Professionals
	Hotspot 2.0 WLPC Wireless LAN Weekly EP 49	Wireless LAN Professionals
	Real World Protocol Analysis Peter Mackenzie WLPC_EU Lisbon 2017	Wireless LAN Professionals
	Next Generation Troubleshooting with Meraki Wireless Devin Barger WLPC Prague 2018	Wireless LAN Professionals

Table 1.0 - Video Help