How Can I Check Common Wifi Issues
Understanding the Functionality of Internet Addressing
When navigating the Internet, you are assigned a Public IPv4 address, such as 88.24.239.206, or an IPv6 address like 2000:da51:3fad:1ae2:4622:cb57:2cf9:1c97. These addresses can be verified by visiting https://test-ipv6.com/. However, conveying these addresses to individuals who lack technical expertise, or even referencing MAC addresses like a3:87:c9:e5:f9:35, proves to be error-prone and becomes complex in a short amount of time. In addition, this method fails to provide any historical data, especially regarding past issues.
Navigating the World Wide Web
To access a web page, such as https://koss.net, your computer initially connects to a DNS server to translate the host portion (koss) combined with the Top Level Domain (net) of the URL into an IP address, such as 51.162.72.13. Every web request sent by your computer and browser includes the type, for example: Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0
The Significance of Default Gateways
Your default gateway is typically an automatically configured address via DHCP. A default gateway, such as 10.7.164.164 (although they usually end in .1 or .254 depending on the scope size), is where your computer forwards all of its traffic to be routed further. For IPv6, in-depth information is available at how-to-fix-ipv6-connectivity/, but you can also check on Mac or Linux with this 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 10.7.164.164 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:a877:86b6:8cc6:8f6d%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): {143.157.2.63, 237.126.26.123}
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 a3:87:c9:e5:f9:35
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 5a:97:ab:de:6e:38
}
Resolve Issues with Wired and Wireless Network Connection
When it comes to transmitting data to your router, you might be using a wired or wireless (Wi-Fi) medium at the physical and data layer.
Steps to Take for Apple macOS / OSX Troubleshooting
No matter which version of OSX/macOS you are currently using, whether it’s 10.11.5, 11.6.5, or 12.1.7, there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that embrace remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
One valuable tool on OSX/macOS is the sudo wdutil info, which provides a dump of current wireless related settings to the CLI and can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is point-in-time only in relation to wireless, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs in /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose, which will give 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. Keep in mind the file sizes, which are approximately 300MB.
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