How Do You Support Common Wifi Router Issues
Understanding Internet Protocol Addressing
When using the Internet, you are assigned a unique Public IPv4 address, such as 228.202.19.223, or an IPv6 address, like 2000:3b2d:76c1:4aa9:9037:2517:672a:6e0. This can be verified through https://test-ipv6.com/. However, explaining and communicating these addresses, as well as MAC addresses like 13:66:53:4c:6a:fb, can be confusing and prone to errors, especially for non-technical individuals. Additionally, it does not provide any historical data related to previous issues that may have occurred.
Navigating the World Wide Web
Accessing a website, such as https://jaskolski.co, involves the initial interaction with a DNS server to convert the host portion (jaskolski) combined with the Top Level Domain (co) of the URL into an IP address, such as 235.224.2.94. Furthermore, your computer and browser include its type in all web requests, for example: Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0.
Understanding the Significance of Default Gateways
The default gateway is typically an automatically configured address through DHCP, such as 172.27.224.38 (often ending in .1 or .254, depending on the scope size). This is the point where your computer directs all its traffic to be routed onwards. For IPv6, a detailed explanation is available in our article how-to-fix-ipv6-connectivity/, and it can be checked on Mac or Linux 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 172.27.224.38 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 fe80:9387:6267:2172:9e7a%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): {56.22.30.78, 9.192.221.110}
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 13:66:53:4c:6a:fb
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 64:8d:38:66:83:87
}
Solutions for Connectivity Issues
When troubleshooting connectivity issues, it’s important to consider both wired and wireless options at the physical and data layer. Whether you are using a wired connection or a wireless (Wi-Fi) medium to send data to your router, there are a variety of potential solutions to explore.
Troubleshooting Methods for Apple macOS / OSX
Regardless of the version of OSX/macOS you are using, whether it’s 10.11.7, 11.4.8, or 12.0.1, there are numerous tools available for troubleshooting connectivity issues. However, these tools may not provide a comprehensive set of correlated values over time, which is especially important for teams that operate remotely and practice Work From Anywhere (WFA).
Utilizing Pre-Installed Scripts
One valuable tool on OSX/macOS is the sudo wdutil info, which provides a detailed dump of current wireless settings and can also be configured to generate specific logs for troubleshooting purposes. In addition, the sysdiagnose tool can be used to generate a wide range of logs, although many are only relevant to a specific point in time with respect to wireless connectivity, just like wdutil.
To run the sysdiagnose tool in the background and generate logs in /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. Alternatively, to run it interactively, use the command sudo /usr/bin/sysdiagnose, which will provide a privacy warning and then open Finder in the appropriate location. Just be aware of the file sizes, which are approximately 300MB.
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