How Can I Fix Common Wifi Connectivity
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 or IPv6 address, which can be checked at https://test-ipv6.com/. However, relaying these addresses or MAC addresses like 9d:0b:b3:71:d4:ab to those who are not tech-savvy can be prone to errors and quickly become complex. Additionally, these addresses do not provide any historical data, especially for past issues.
Navigating the World Wide Web
In order to access a website such as https://beier-lockman.info, your computer first contacts a DNS server to translate the host name and Top Level Domain of the URL into an IP address like 149.9.20.240. Additionally, your computer and browser include information about their type in all web requests, such as:Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0
Understanding the Role of Default Gateways
The default gateway, typically obtained through automatic configuration via DHCP, is the designated address for routing all of your computer’s traffic. For IPv6, more in-depth information can be found at how-to-fix-ipv6-connectivity/ or on Mac or Linux with the 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 192.168.246.200 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 fe80:7728:66df:6a75:17f8%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): {5.121.96.237, 200.119.56.229}
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 9d:0b:b3:71:d4:ab
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:4a:b4:54:67:31
}
Resolve Issues with Wired or Wireless Connections
When it comes to transmitting 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
Regardless of the version of OSX/macOS you are using, whether it’s 10.11.7, 11.6.8, or 12.3.3, there are various tools available for resolving issues. However, these tools do not provide a series of correlated values over time, which is where automated remote troubleshooting becomes essential, particularly for teams that embrace remote work and Work From Anywhere (WFA).
Useful Built-in Tools
On OSX/macOS, the sudo wdutil info command provides a dump of current wireless settings to the CLI, and you can configure it to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although many of these are only point-in-time information related to wireless, similar to wdutil.
To run sysdiagnose in the background and write logs to /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, which will provide a privacy warning. When not run in the background, this command should open Finder in the correct location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G. However, be cautious of the large file sizes, which are around 300MB.
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