How To Support Wifi Connectivity
Understanding Internet Addressing
When accessing the Internet, you are assigned an IP address, which could be a Public IPv4 address such as 195.194.39.187 or an IPv6 address like 2000:f6a0:7635:b54c:f81a:fa48:1f25:ec34. You can verify this information at https://test-ipv6.com/. However, sharing these addresses, or even MAC addresses like 67:f3:6e:f3:01:27, can be challenging for non-technical individuals and lacks historical data.
Navigating the World Wide Web
To access a website like https://schuster-howe.co, your device makes an initial connection to a DNS server to translate the URL into an IP address, such as 195.41.189.1. Additionally, your computer and browser send specifications with each web request, for example:
Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
Significance of Default Gateways
By default, your device is assigned a gateway address through DHCP, such as 192.168.19.112 (commonly ending in .1 or .254 depending on the network’s scope). This gateway serves as the point where your device directs all its outgoing traffic. For troubleshooting IPv6 connectivity on Mac or Linux, refer to our detailed guide at how-to-fix-ipv6-connectivity/.
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 192.168.19.112 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 fe80:869c:c31b:bd7:2943%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): {190.110.161.168, 229.52.129.168}
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 67:f3:6e:f3:01:27
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 6c:10:ed:11:b7:df
}
Resolving Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you might 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 currently using, such as 10.12.2, 11.1.1, or 12.2.7, there are a variety of troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes essential, especially for teams that are transitioning to remote work and embracing the Work From Anywhere (WFA) concept.
Useful Built-in Scripts
One particularly useful tool on OSX/macOS is the sudo wdutil info, which provides a dump of the current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. In addition, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only related to wireless at a specific point in time, similar to wdutil.
To run it in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose, which will prompt 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 Cmd+Shift+G in Finder. Be mindful of the file sizes, which are around 300MB.
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