Test Wifi No Access
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 address such as 131.35.192.93 or an IPv6 address like 2000:e5f0:350:9390:4f0e:a288:1cbe:8a76. Verification can be done via https://test-ipv6.com/. However, for those not well-versed in technology, conveying these addresses, including MAC addresses like 39:41:24:6d:5b:7d, can quickly become complex. Furthermore, this method does not provide any historical data, particularly regarding past issues.
Navigating the World Wide Web
When accessing a web page such as https://christiansen.biz, a DNS server is initially contacted to convert the host portion (christiansen) together with the Top Level Domain (biz) of the URL to an IP address like 243.9.167.15. With each web request, your computer and browser sends its type like so: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
The Significance of Default Gateways
Typically, your default gateway is automatically configured through DHCP. This results in obtaining a default gateway such as 192.0.0.71 (though they generally end in .1 or .254 depending on the scope size), which serves as the location where your computer sends all its traffic to be routed onwards. To explore further on IPv6, refer to our in-depth guide on how-to-fix-ipv6-connectivity/. Additionally, this procedure can be verified on Mac or Linux 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 192.0.0.71 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:fca2:3b7b:b98e:6ae4%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): {13.164.194.103, 127.157.239.248}
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 39:41:24:6d:5b:7d
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 dd:a5:43:2f:bc:58
}
Fixing Connection Issues for Wired and Wireless Networks
When it comes to transferring data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Resolving Problems on Apple macOS / OSX
Regardless of whether you are running OSX/macOS 10.14.8, 11.2.9, or 12.2.7, there is a wide array of troubleshooting tools available. However, manual interventions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that have embraced remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
One extremely 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. Additionally, the more comprehensive sysdiagnose tool can be used to generate a variety of logs related to wireless issues, although much of it is only relevant at a specific point in time, similar to wdutil.
To run the sysdiagnose tool in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, you can use the command sudo /usr/bin/sysdiagnose (although it doesn’t involve much interaction) and it will give a privacy warning. When not run in the background, it should open Finder in the appropriate location, or you can navigate to /var/tmp manually or use Finder with Cmd+Shift+G to point Finder to the path. Keep in mind that the file sizes are approximately 300MB.
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