How Do You DiagnOSe Wifi Internet Issues

A Closer Look at Internet Addressing

When using the Internet, you are likely to have a Public IPv4 address, such as 240.169.47.220, or an IPv6 address, like 2000:13ef:fda:c455:8d0c:bc64:1f08:e784. These can be verified from https://test-ipv6.com/. However, for those who are not particularly tech-savvy, trying to communicate these addresses or even calling out MAC addresses, like 0d:c8:26:99:12:2b, can be prone to errors and quickly become complex. Furthermore, this method does not provide any historical data, especially when dealing with past issues.

Navigating the World Wide Web

When accessing a website like https://quitzon.net, the first step is to access a DNS server to convert the host portion (quitzon) combined with the Top Level Domain (net) of the URL into an IP address, such as 96.56.202.35. Your computer and browser actually include its type with every web request, for example:
Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36.

Understanding the Significance of Default Gateways

Your default gateway is typically an automatically configured address via DHCP. You receive a default gateway, such as 192.0.0.157 (although they usually end in .1 or .254 depending on the scope size), and this is where your computer sends all its traffic to be routed onwards. For IPv6, a more in-depth explanation can be found at how-to-fix-ipv6-connectivity/, but you can check on Mac or Linux using:

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  192.0.0.157    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:eba2:ddca:5598:b3be%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): {105.143.170.102, 182.64.167.104}
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 0d:c8:26:99:12:2b
  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 3c:30:15:f2:fc:0c
}

Fixing Connectivity Issues for Wired and Wireless Networks

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

Solutions for Apple macOS / OSX Users

Regardless of whether you are using OSX or macOS version 10.13.4, 11.1.4, or 12.2.9, 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 practice remote work and Work From Anywhere (WFA).

Utilizing Built-in Scripts for Assistance

An extremely useful tool 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 relevant to wireless during a specific point in time, similar to wdutil.

Running sudo nohup /usr/bin/sysdiagnose -u & will execute it in the background and write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (even though there is minimal interaction), you can use
sudo /usr/bin/sysdiagnose, which will prompt 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 locate the path. Keep in mind that the file sizes are around 300MB more or less.

Possibly Helpful Videos

Video	Title	Channel
	Benefits of WPA3, Enhanced Open, and Easy Connect P. Ebbecke, P. Correll WLPC Prague 2018	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
	Securing the World's Most Dangerous Wi-Fi Network Colin Vallance WLPC Phoenix 2020	Wireless LAN Professionals
	WLAN Troubleshooting David Coleman WLPC US Phoenix 2016	Wireless LAN Professionals

Table 1.0 - Video Help