How Can I DiagnOSe Common Wifi Issues
Understanding Internet Addressing
When using the Internet, you are assigned either a Public IPv4 address similar to 163.13.125.128 or an IPv6 address like 2000:a78c:bd6c:e19b:1c55:30d8:ad46:fe7. You can verify this information by visiting https://test-ipv6.com/. However, these addresses can be complex and error-prone for ordinary users to communicate or remember, including MAC addresses such as 14:74:38:7c:b1:0c. Moreover, they do not provide historical data about past issues.
Navigating the World Wide Web
To access a website like https://goodwin-huel.com, your computer initially contacts a DNS server to convert the host portion (goodwin-huel) in combination with the Top Level Domain (com) of the URL into an IP address, such as 17.99.142.23. Additionally, your computer and web browser transmit specific information with every web request, for example: Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
The Significance of Default Gateways
The default gateway is generally an automatically assigned address through DHCP. It may be a default gateway like 192.168.151.50 (often ending in .1 or .254, depending on the scope size), to which your computer directs all its traffic for further routing. For IPv6, you can delve deeper into the topic through how-to-fix-ipv6-connectivity/ or 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 192.168.151.50 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:e559:7421:4911:7202%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): {198.247.171.95, 156.55.245.192}
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 14:74:38:7c:b1:0c
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 69:1b:78:57:66:90
}
Resolve Issues with Wired and Wireless Connections
When sending data to your router, you may be utilizing either a wired or a wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX
No matter which version of OSX/macOS you are currently using - whether it is 10.11.8, 11.4.7, or 12.3.7, there are various tools available for resolving issues. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that embrace remote work and Work From Anywhere (WFA).
Handy Built-in Scripts
A useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings to the CLI and can be configured to generate specific troubleshooting logs. Furthermore, the sysdiagnose tool can be employed to generate a wide range of logs, although much of the information pertains to wireless settings at a specific moment in time, similar to wdutil.
To run sysdiagnose 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 sudo /usr/bin/sysdiagnose, but be mindful of the large file sizes of about 300MB. After running the command, Finder should open in the correct location, or you can navigate to /var/tmp using Cmd+Shift+G.
Possibly Helpful Videos
P.S. Tips For Remote Network and Client Support
Digital work requires reliable connectivity. Whether for low latency or regular data streams, Wi-Fi, DNS, and network issues cause teams to lose time and productivity. Even worse is when support teams waste time trying to recreate and isolate issues! See how PanSift saves time, money, and frustration on all sides with instant remote troubleshooting 🏠🏝🛰.
