How Do You Test Common Wifi Issues
Understanding Internet Addressing
When you’re using the Internet, you will be assigned a Public IPv4 address such as 174.61.185.2 or an IPv6 address like 2000:8:f5b2:7342:ad81:79cd:601e:4677. You can verify this information by visiting https://test-ipv6.com/. However, for those who are not well-versed in technology, communicating these addresses or even mentioning MAC addresses like 4f:97:25:30:6c:b9 can become error-prone and overly complex. Furthermore, it doesn’t provide any historical data, especially from previous incidents.
Navigating the World Wide Web
When trying to access a webpage like https://mosciski.info, the first step is to connect to a DNS server in order to translate the host portion (mosciski) combined with the Top Level Domain (info) of the URL into an IP address such as 149.145.246.31. As your computer and browser transmit basic information with each 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
Typically, your default gateway is assigned through DHCP and is usually an automatically configured address like 10.176.158.163 (although they generally end in .1 or .254 depending on the size of the scope). This is where your computer directs all of its traffic to be routed onward. For more information on IPv6, you can delve into how-to-fix-ipv6-connectivity/, or check 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 10.176.158.163 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 fe80:5f4:290b:fbf9:bf5a%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): {131.119.122.150, 122.22.198.15}
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 4f:97:25:30:6c:b9
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 a0:48:f2:8f:0a:fa
}
Fixing Connectivity Issues in Wired and 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 Tips for Apple macOS / OSX Users
Regardless of whether you are working on OSX/macOS version 10.13.8, 11.4.7, or 12.0.7, there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes invaluable, particularly for teams that embrace remote work and Work From Anywhere (WFA).
Internal Scripts for Assistance
An extremely 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 logs for troubleshooting. Furthermore, the sysdiagnose tool can be used to produce a wide range of logs, although many are only relevant to wireless in the present moment, much like the wdutil.
To run it in the background and generate logs, you can use the command sudo nohup /usr/bin/sysdiagnose -u &, which will write the logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can use the commandsudo /usr/bin/sysdiagnose, which will trigger a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to point Finder to the path. However, be mindful of the file sizes, which are approximately 300MB, more or less.
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