Fix Common Wifi Connectivity
Understanding Internet Addressing
When using the Internet, you will be assigned a Public IPv4 or IPv6 address. These addresses can be checked at https://test-ipv6.com/. Communicating these addresses to non-technical individuals or even referencing MAC addresses can be complex and error-prone. Additionally, historical data on previous issues may not be available.
Navigating the World Wide Web
Accessing a web page such as https://kemmer-smitham.biz involves initially connecting to a DNS server, which translates the host portion and Top Level Domain of the URL to an IP address like 84.231.22.55. Your computer and browser send their type with all web requests, for example:
Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
The Significance of Default Gateways
The default gateway, typically automatically configured via DHCP, serves as the address where your computer sends all its traffic to be routed onwards, such as 192.168.73.61 for IPv4. For IPv6, more information can be found at how-to-fix-ipv6-connectivity/. Mac or Linux users can verify their default gateway with:
ip -6 route show
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 192.168.73.61 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:e117:b77a:9622:ded8%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): {246.197.154.209, 245.120.33.9}
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 31:96:d4:ba:62:2f
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 ff:e3:78:ac:cf:7e
}
Resolving Issues with Wired and Wireless Connections
When transferring data to your router, you may be using 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’s 10.13.2, 11.4.1, or 12.3.9 - there are various tools available for troubleshooting. However, these tools and manual actions do not provide a series of correlated values over time, which is where remote troubleshooting comes in handy, especially for teams that are embracing remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
On OSX/macOS, the sudo wdutil info tool provides a dump of the current wireless settings to the CLI and can also be configured to generate specific logs for troubleshooting. Another comprehensive tool is the sysdiagnose, which can produce a wide range of logs (although many of them provide point-in-time information related to wireless, similar to wdutil).
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will create 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 issue a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G or manually search for the path. Keep in mind that the file sizes are approximately 300MB.
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