Check Wifi Issues
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 address, such as 225.162.11.82, or an IPv6 address, like 2000:e38f:5438:9272:e0d5:ba4f:6c25:5a9f. You can verify this by visiting https://test-ipv6.com/. However, conveying these addresses to individuals who are not technically inclined, or even sharing MAC addresses such as f2:e6:92:1c:5d:2b, can be prone to error and become complex. Moreover, this approach lacks historical data, particularly in the context of past issues.
Navigating the World Wide Web
In order to access a website like https://hilpert-weimann.net, you begin by contacting a DNS server to convert the host portion (hilpert-weimann) along with the Top Level Domain (net) of the URL into an IP address, such as 152.147.175.129. Whenever your computer and browser make web requests, they include information about their type, for example: Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
Significance of Default Gateways
The default gateway is typically an automatically assigned address through DHCP. It may be a default gateway like 10.138.203.63 (though they generally end in .1 or .254 depending on the scope size), and this is where your computer sends all its traffic to be routed onwards. For IPv6, there is a detailed overview available at how-to-fix-ipv6-connectivity/, and users can verify this on Mac or Linux by using the following 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 10.138.203.63 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 fe80:2874:29a5:fd48:ba6%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): {159.180.119.195, 123.116.210.213}
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:e6:92:1c:5d:2b
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 fb:58:d6:b7:6c:ab
}
Solutions for Wired and Wireless Connectivity Issues
When it comes to sending data to your router, you may encounter connectivity issues at the physical and data layer, whether you are using a wired or wireless (Wi-Fi) medium.
Troubleshooting on Apple macOS / OSX
Regardless of the version of OSX/macOS you are using, whether it’s 10.15.5, 11.1.9, or 12.0.4, there are various 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 invaluable, particularly for teams operating remotely or embracing a Work From Anywhere (WFA) model.
Use of Built-in Scripts
A 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 purposes. Furthermore, the sysdiagnose tool offers a more comprehensive range of logs, although many are point-in-time only in relation to wireless, similar to wdutil.
To run the sysdiagnose tool 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 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 using Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB.
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