DiagnOSe Wifi Router Issues
Understanding Internet Addressing
When utilizing the Internet, individuals may be assigned a Public IPv4 address such as 209.143.102.154 or an IPv6 address like 2000:2f46:5f54:dae9:8a38:f5be:ffe0:25ce, which can be verified at https://test-ipv6.com/. However, communicating these addresses, including MAC addresses like 41:9d:4e:34:57:fc, can become complex and error-prone, particularly for those who are not familiar with technical jargon. Moreover, it does not provide historical data, especially from past issues.
Navigating the World Wide Web
Accessing a website, such as https://howe.info, involves the initial step of accessing a DNS server to translate the host portion (howe) combined with the Top Level Domain (info) of the URL into an IP address like 139.79.89.124. Furthermore, all web requests sent from your computer and browser include its type, for example, Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts).
Understanding Default Gateways
The default gateway, typically an automatically configured address via DHCP, is assigned to your computer, such as 192.168.71.84 (often ending in .1 or .254 depending on the scope size), where all outgoing traffic from your computer is routed. For IPv6, a detailed guide on how-to-fix-ipv6-connectivity/ is available, and you can also verify it on Mac or Linux through:
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 192.168.71.84 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 fe80:7ef6:566:b684:cbde%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): {172.219.199.49, 100.118.226.40}
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 41:9d:4e:34:57:fc
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 64:5d:6b:b4:54:cd
}
Resolving Wired and Wireless Connectivity Issues
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
Whether you’re running OSX/macOS versions like 10.15.1, 11.6.7, or 12.2.3, there are various troubleshooting tools available. However, the manual interventions and scripts do not provide a series of interconnected values over time. This is where automated remote troubleshooting becomes crucial, especially for teams engaged in remote work and Work From Anywhere (WFA) setups.
Effective Built-in Utilities for Troubleshooting
One of the helpful tools on OSX/macOS is the sudo wdutil info, which displays the current wireless settings and can be set up to generate specific logs for troubleshooting purposes. Additionally, the comprehensive sysdiagnose tool can be used to generate a wide range of logs, although most of it is related to wireless data and is not historical like wdutil.
You can run sudo nohup /usr/bin/sysdiagnose -u & in the background, which will write logs to /var/tmp/<blah>.tar.gz. 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 Finder with Cmd+Shift+G. Keep in mind that the file sizes are around 300MB.
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P.S. Tips For Remote Network and Client Support
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