How To Fix Common Wifi Connectivity
Understanding the Functioning of Internet Addressing
When using the Internet, it is common to receive a Public IPv4 address such as 154.82.181.107 or an IPv6 address like 2000:28f6:3c21:ad43:6086:b458:2a0d:5f67. You can verify this information by visiting https://test-ipv6.com/. However, sharing these addresses with individuals who are not tech-savvy or even mentioning MAC addresses like 77:3d:ea:a9:c7:45 can lead to errors and can become complex quickly. Moreover, this method does not provide any historical data, particularly regarding past issues.
Navigating the World Wide Web
When attempting to access a website such as https://ratke.biz, the first step involves reaching out to a DNS server to convert the host part (ratke) along with the Top Level Domain (biz) of the URL into an IP address, for example, 116.223.191.128. Your computer and browser include information about their type with each web request, such as Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285.
Significance of Default Gateways
Typically, your default gateway is an address that is automatically configured through DHCP. This default gateway, like 192.168.73.64 (although they generally end in .1 or .254 based on the scope size), is where your computer forwards all its traffic to be further routed. For IPv6, detailed information on this topic can be found here. You can also perform this check on Mac or Linux by using the following command:
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 192.168.73.64 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:e928:d3c8:eead:eaa5%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): {115.191.71.253, 190.110.220.170}
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 77:3d:ea:a9:c7:45
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 84:e4:02:cb:ee:e5
}
Fixing Connectivity Issues for Wired or Wireless Networks
When it comes to transmitting data to your router, you might be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting for Apple macOS / OSX Users
Irrespective of whether you are running OSX/macOS versions such as 10.13.7, 11.3.2, or 12.2.2, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a set of correlated values over a period of time. This is where automated remote troubleshooting becomes invaluable, especially for teams that are inclined towards remote work and Work From Anywhere (WFA) environments.
Leveraging Built-in Scripts for Assistance
One extremely useful tool on OSX/macOS is the sudo wdutil info command, which offers a dump of current wireless settings to the CLI, and can also be configured to generate specific logs for troubleshooting purposes. Moreover, the sysdiagnose tool can be used to generate a multitude of logs, although most of the data relates specifically to wireless and is only relevant at a specific point in time, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs in /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can use the sudo /usr/bin/sysdiagnose command, which will prompt a privacy warning. If not running in the background, it should open Finder in the correct location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G. However, be mindful of the file sizes, which range from about 300MB.
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