How Can I Test Common Wifi Router Issues

Understanding Internet Addressing Systems

When it comes to the Internet, individuals may be assigned a Public IPv4 address, such as 44.74.152.82, or an IPv6 address, such as 2000:ff3d:b76c:cca7:e1a1:fe7c:430c:23f. Verification of these addresses can be done through https://test-ipv6.com/. However, conveying these addresses, or even referring to MAC addresses like b8:a3:98:7c:82:15, to those who are not technologically inclined can often result in errors and confusion. Furthermore, this method fails to provide any historical data, especially in cases of past issues.

Navigating the World Wide Web

The process of reaching a web page, such as https://smitham.org, involves initially accessing a DNS server to convert the host portion (smitham) combined with the Top Level Domain (org) of the URL into an IP address, like 116.177.231.254. Whenever a web request is made, your computer and browser also send their specifics along, as in the example below:

Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A

The Significance of Default Gateways

Typically assigned automatically via DHCP, your default gateway, such as 10.177.155.169 (typically ending in .1 or .254 based on the scope size), serves as the central hub for all outgoing traffic from your computer. For IPv6 connectivity resolutions, a detailed guide can be found at how-to-fix-ipv6-connectivity/. On Mac or Linux systems, the gateway can be verified with the following command:

<br>

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  10.177.155.169    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   fe80:8eef:284e:ce22:6a44%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): {220.103.24.240, 254.176.181.13}
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 b8:a3:98:7c:82:15
  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 25:56:cc:0e:25:90
}

Solutions for Resolving Issues with Wired and Wireless Connection

When transmitting data to your router, you may be utilizing either a wired or a wireless (Wi-Fi) medium at the physical and data layer.

Steps to Take for Apple macOS / OSX Troubleshooting

Regardless of the specific version of OSX/macOS you are currently using, whether it’s 10.13.2, 11.6.5, or 12.2.8, there are various tools available for troubleshooting. However, manual actions and scripts may not provide a consistent set of correlated values over time. This is where automated remote troubleshooting becomes invaluable, particularly for teams that embrace remote work and Work From Anywhere (WFA).

Utilizing In-Built Scripts for Assistance

One highly useful tool on OSX/macOS is the sudo wdutil info command, which provides a detailed dump of the current wireless settings in the CLI. This command can also be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool offers a more comprehensive option, producing a wide range of logs (although many of these are point-in-time only in relation to wireless, similar to wdutil).

Running sudo nohup /usr/bin/sysdiagnose -u & in the background will create logs in /var/tmp/<blah>.tar.gz for you. For an interactive run (although there is minimal interaction), you can use sudo /usr/bin/sysdiagnose, which will provide a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp manually or use Finder with Cmd+Shift+G to locate the path. Keep in mind that the file sizes are approximately 300MB or so.

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