How To Test Wifi Issues
The Functioning of Internet Addressing
When connected to the Internet, you are assigned a Public IPv4 address (e.g. 114.33.184.240) or an IPv6 address (e.g. 2000:5182:39c4:6aa0:d2a6:65ba:bd31:8388). You can verify this information by visiting https://test-ipv6.com/. However, translating these addresses or MAC addresses (e.g. 77:57:84:ac:65:04) can be quite complicated and error-prone, especially for those who are not tech-savvy. Furthermore, this approach lacks historical data, particularly during past issues.
Navigating the World Wide Web
Accessing a website like https://ferry.net involves contacting a DNS server to convert the host name (ferry) and the Top Level Domain (net) of the URL into an IP address (e.g. 65.218.10.20). Whenever your computer and browser make web requests, they transmit information on their type, such asMozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
Understanding the Significance of Default Gateways
The default gateway is typically an address that is automatically configured through DHCP. This gateway, which usually ends in .1 or .254 depending on the scope size, is where your computer directs all its traffic for further routing. For IPv6, you can refer to our in-depth article on 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 192.168.207.216 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 fe80:6cdc:f262:4692:1b89%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): {59.233.17.243, 208.91.43.231}
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 77:57:84:ac:65:04
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 ba:63:ea:f6:22:58
}
Resolving Connectivity Issues for Wired or Wireless Networks
When it comes to transmitting data to your router, you may be using a wired or wireless (Wi-Fi) connection at the physical and data layer.
Troubleshooting Methods for Apple macOS / OSX
Regardless of whether you are using OSX/macOS version 10.11.5, 11.6.2, or 12.3.2, there are various tools available for troubleshooting. However, the manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that adopt remote work and Work From Anywhere (WFA) practices.
Useful Built-in Utilities
A particularly valuable tool on OSX/macOS is the sudo wdutil info command, which provides a dump of the current wireless settings to the command line interface, and can be configured to generate specific logs for troubleshooting purposes. Alternatively, the sysdiagnose tool offers a more comprehensive option for generating a wide range of logs, although many are only relevant at a specific point in time, similar to wdutil.
To run the sysdiagnose tool in the background and generate logs in /var/tmp/<blah>.tar.gz, you can 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, but keep in mind that it will open Finder in the correct location or you can navigate to /var/tmp manually or by using Finder with Cmd+Shift+G. Be mindful of the file sizes, which are around 300MB.
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