Check Common Wifi Issues
Understanding Internet Addressing Principles
When it comes to the internet, you may be assigned a Public IPv4 address such as 165.184.47.93 or the longer IPv6 address, such as 2000:1556:2828:113a:e58b:d5f1:1c6f:c739. You can verify your address by visiting https://test-ipv6.com/. However, conveying these addresses to non-technical individuals or even referencing MAC addresses like cb:75:b6:95:28:f0 can be prone to mistakes and quickly become complex. Furthermore, this method does not provide any historical data, especially about past issues.
Navigating the World Wide Web
When accessing a website like https://roob.com, you begin by reaching out to a DNS server to convert the host portion (roob) combined with the Top Level Domain (com) of the URL into an IP address, such as 11.195.53.29. Your computer and browser automatically includes its type in all web requests, for example:
Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0
Understanding the Significance of Default Gateways
Your default gateway is typically an address that is automatically configured via DHCP. This address, such as 192.168.46.179 (usually ending in .1 or .254 based on the scope size), is where your computer sends all its traffic to be routed onward. For IPv6, comprehensive guidance is available on how-to-fix-ipv6-connectivity/, and there are ways to check on Mac or Linux with:
<br>
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 192.168.46.179 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 fe80:7fd0:f943:f0c8:2fc1%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): {166.201.145.228, 152.93.235.45}
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 cb:75:b6:95:28:f0
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 45:48:18:1b:b2:03
}
Resolve Wired and Wireless Connection Issues
When it comes to transmitting data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Methods for Apple macOS / OSX Users
Regardless of the version of OSX/macOS you are using, whether it’s 10.15.5, 11.2.5, or 12.3.8, 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 essential, particularly for teams that have embraced remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
One 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. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only applicable at a specific point in time, similar to wdutil.
By running sudo nohup /usr/bin/sysdiagnose -u &, the tool will generate logs in the background and save them to /var/tmp/<blah>.tar.gz. Alternatively, you can run sudo /usr/bin/sysdiagnose interactively, which will display 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 navigate to the path. Keep in mind that the file sizes are approximately 300MB.
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