How Can I Support Common Wifi Router Issues
The Functioning of Internet Addressing
When using the internet, you will be assigned a Public IPv4 address, such as 226.163.0.199, or an IPv6 address, such as 2000:e250:3e8c:8e84:6b37:2b46:4083:8d78. You can verify this information by visiting https://test-ipv6.com/. However, explaining or recalling these addresses, and even mentioning MAC addresses like 68:78:86:ee:dc:3b, can be prone to errors and can become complex. Moreover, this does not provide historical data, especially for past issues.
Navigating the Internet
When trying to access a website like https://barrows.name, you will first connect to a DNS server to convert the host name (barrows) along with the Top Level Domain (name) of the URL to an IP address, such as 64.120.127.5. Your computer and browser sends its type with all web requests, for example: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
The Significance of Default Gateways
Normally, your default gateway is an address that is automatically configured via DHCP. You receive a default gateway, such as 172.27.161.137 (although they typically end in .1 or .254 depending on the size of the scope), and this is the location where your computer forwards all its traffic for further routing. For IPv6, there is an in-depth discussion available at how-to-fix-ipv6-connectivity/, but you can verify it on Mac or Linux using the following code:
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 172.27.161.137 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 fe80:10ef:8ea4:3e10:15ac%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): {183.6.25.215, 86.120.180.36}
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 68:78:86:ee:dc:3b
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 c7:83:06:4e:14:1e
}
Fixing Connectivity Issues on Wired or Wireless Networks
When it comes to transferring data to your router, you may be relying on a wired or wireless (Wi-Fi) medium at the physical and data layer.
Resolving Problems on Apple macOS / OSX Operating Systems
Regardless of whether you are running OSX/macOS version 10.14.5, 11.3.4, or 12.1.9, there are various troubleshooting tools available. However, these tools do not provide a set of correlated values over time, which is where automated remote troubleshooting becomes invaluable, particularly for teams that are embracing remote work and Work From Anywhere (WFA).
Utilizing Pre-installed Scripts for Assistance
One useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings to the command-line interface and can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only relevant to wireless connectivity at a specific point in time, similar to wdutil.
To run it 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 (although there is minimal interaction), 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 or use Cmd+Shift+G to point Finder to the path. It’s important to note that the file sizes are approximately 300MB.
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