How Can I Check Wifi Connectivity
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 address, such as 17.191.144.35, or an IPv6 address like 2000:8316:b78c:e258:9617:4a68:8b3a:1830. You can verify these addresses at https://test-ipv6.com/. However, conveying these addresses, or even MAC addresses like f2:19:bd:79:23:27, can be complex for those who are not tech-savvy. Moreover, this method does not provide historical data, especially for past issues.
Navigating the World Wide Web
When accessing a website like https://larkin.com, you first connect to a DNS server to translate the host portion (larkin) combined with the Top Level Domain (com) of the URL to an IP address like 122.208.238.238. Additionally, your computer and browser include information about the type of web requests, such as 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 is typically an automatically configured address through DHCP. Your computer is assigned a default gateway, such as 192.168.183.186 (often ending in .1 or .254 depending on the scope size), to route all its traffic. For IPv6, refer to our in-depth guide at how-to-fix-ipv6-connectivity/ or use the following commands on Mac or Linux:
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 192.168.183.186 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 fe80:9b2e:d027:8e70:b1c3%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): {102.251.42.32, 171.195.120.213}
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 f2:19:bd:79:23:27
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 78:92:fa:c5:2a:b7
}
Diagnosing and Resolving Connectivity Issues
When dealing with connectivity issues, it’s crucial to determine whether the problem lies in the wired or wireless (Wi-Fi) medium used to transmit data to the router, operating at the physical and data layer.
Troubleshooting on Apple’s macOS / OSX Platform
Regardless of your version of OSX/macOS, be it 10.13.1, 11.1.2, or 12.3.4, there is a wide array of tools available for troubleshooting. However, these manual actions and scripts do not provide a continuous series of correlated values over time, making automated remote troubleshooting invaluable, especially for teams embracing remote work and Work From Anywhere (WFA).
Leveraging Built-in Scripts for Assistance
On the OSX/macOS platform, the sudo wdutil info tool proves to be immensely helpful, providing a comprehensive dump of current wireless settings in the CLI, and can also be configured to generate specific troubleshooting logs. Furthermore, the sysdiagnose tool presents a more exhaustive option for logging, albeit with some limitations in terms of its real-time capabilities for wireless troubleshooting, much like wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs at /var/tmp/<blah>.tar.gz. For an interactive (albeit minimal interaction) approach, the command sudo /usr/bin/sysdiagnose will trigger a privacy warning and prompt Finder to navigate to the correct location, where the file sizes typically hover around 300MB.
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