How Do You Fix Wifi No Access
Understanding Internet Protocol Addressing
When using the internet, you are assigned a Public IPv4 address such as 59.112.101.99 or an IPv6 address like 2000:536c:50a8:ed81:d6b0:e7bb:235b:6cfc. It is possible to verify this information by visiting https://test-ipv6.com/. However, communicating these addresses, and even mentioning MAC addresses like 53:cd:d7:8e:b8:61, can be prone to errors and become complex. Moreover, this approach does not provide any historical data, particularly when troubleshooting past issues.
Navigating the World Wide Web
When attempting to access a web page like https://mckenzie.org, the process begins by reaching out to a DNS server to translate the host portion (mckenzie) combined with the Top Level Domain (org) into an IP address such as 55.22.199.45. Interestingly, every web request from your computer and browser includes its type, for example: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko.
Significance of Default Gateways
The default gateway is usually an automatically assigned address through DHCP. It typically resembles something like 192.0.0.172 (although they commonly end in .1 or .254 based on the scope size) and this is where all the traffic from your computer is routed to for further processing. For IPv6, we provide an in-depth discussion on the topic in how-to-fix-ipv6-connectivity/. However, on Mac or Linux, you can assess this through:
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 192.0.0.172 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:cc1a:8ecf:9665:444d%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): {162.166.27.147, 164.223.70.192}
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 53:cd:d7:8e:b8:61
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 bb:43:3d:96:20:bc
}
Addressing Issues with Wired and Wireless Connections
When transmitting data, whether it’s through a wired or wireless (Wi-Fi) medium, you are operating at the physical and data layer as you send the information to your router.
Troubleshooting Tips for Apple macOS / OSX
Regardless of the version of OSX/macOS you are currently using - whether it’s 10.15.6, 11.5.4, or 12.3.3 - there are various tools available for addressing connectivity issues. However, these manual interventions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes essential, especially for teams engaged in remote work and the Work From Anywhere (WFA) model.
Utilizing Built-in Tools for Assistance
One valuable tool available 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 troubleshooting logs. Moreover, the sysdiagnose tool offers a more comprehensive approach, allowing users to generate a wide array of logs, although many of these are only relevant to a specific point in time, similar to the wdutil tool.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs in /var/tmp/<blah>.tar.gz for you. Alternatively, running sudo /usr/bin/sysdiagnose interactively will provide a privacy warning, and it should open Finder in the correct location or allow you to navigate to /var/tmp, or use Finder with Cmd+Shift+G to specify the location. It’s important to note that the file sizes are approximately 300MB.
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