Fix Wifi Connectivity

Understanding Internet Addressing

When using the internet, you are assigned a Public IPv4 address like 66.134.187.108 or an IPv6 address like 2000:e9bb:daab:5717:40c3:9cb1:b9d8:32bc. The website https://test-ipv6.com/ can be used to verify these addresses. However, explaining these addresses, or MAC addresses like c0:52:11:39:30:30 to those who are not technologically savvy can be prone to errors and quickly become complex. Furthermore, it does not provide any historical data, especially from past issues.

Navigating the Internet

When trying to access a webpage such as https://runolfsdottir-schinner.co, an initial visit to a DNS server is necessary to convert the host portion (runolfsdottir-schinner) combined with the Top Level Domain (co) of the URL into an IP address like 147.190.216.131. Every web request from your computer and browser includes its type, for example:
Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0.

Understanding the Significance of Default Gateways

By default, your gateway is automatically configured through DHCP. This results in a default gateway such as 10.29.81.231 (although they typically end in .1 or .254 depending on the scope size), and it acts as the location where your computer sends all of its traffic to be routed further. For IPv6, a detailed analysis is available at how-to-fix-ipv6-connectivity/, and can be checked on Mac or Linux 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  10.29.81.231    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:b612:5aa0:8cb:a0a2%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): {96.59.35.217, 24.17.253.244}
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 c0:52:11:39:30:30
  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 50:aa:a7:17:19:8a
}

Resolving Issues with Wired and Wireless Connections

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

Troubleshooting Tips for Apple macOS / OSX Users

Regardless of whether you are running OSX/macOS version 10.15.6, 11.6.9, or 12.1.5, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes particularly useful, especially for teams that are embracing remote work and a Work From Anywhere (WFA) approach.

Utilizing Pre-installed Scripts for Assistance

One useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of the current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Moreover, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is related to wireless settings only, similar to wdutil.

To run it in the background and generate logs in /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively (although there is minimal interaction), you can use the command sudo /usr/bin/sysdiagnose, but be prepared for file sizes of about 300MB. After running the command, it should open Finder in the appropriate location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G. However, be mindful of the file sizes, as they can be quite large.

Possibly Helpful Videos

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Table 1.0 - Video Help