How To Fix Common Wifi Router Issues
Understanding Internet Addressing
When using the Internet, you are assigned a unique Public IPv4 address such as 250.100.46.251 or an IPv6 address like 2000:5c10:20fa:effe:ad36:a24f:ac4c:3809. These addresses can be verified at https://test-ipv6.com/. However, for individuals who are not technically inclined, communicating these addresses or even referencing MAC addresses like 04:aa:df:1e:e4:73 can be prone to errors and become complex. It also lacks historical data.
Navigating the World Wide Web
In order to access a webpage like https://rosenbaum.co, the initial step is to connect to a DNS server to convert the host portion (rosenbaum) along with the Top Level Domain (co) of the URL to an IP address such as 102.217.176.124. When making web requests, your computer and browser also include its type, for example: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
Understanding the Significance of Default Gateways
Your default gateway is typically an address that is automatically configured through DHCP. This address, such as 10.111.150.24 (usually ending in .1 or .254 based on scope size), is where your computer directs all its traffic to be routed onward. For IPv6, a detailed explanation is available at how-to-fix-ipv6-connectivity/, but it can be checked on Mac or Linux using:
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 10.111.150.24 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:a536:ff46:2aa8:9fdb%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): {59.0.72.170, 88.198.176.145}
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 04:aa:df:1e:e4:73
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 da:53:5b:a3:1b:fa
}
Resolving Issues with Wired or Wireless Connections
When it comes to transferring data to your router, you might be relying on a wired or wireless (Wi-Fi) medium at the physical and data layer.
Tips for Apple macOS / OSX Users
Regardless of whether you are using OSX/macOS version 10.15.7, 11.6.7, or 12.2.9, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams that are embracing remote work and Work From Anywhere (WFA).
Utilizing Pre-installed Scripts
On OSX/macOS, the sudo wdutil info tool is quite beneficial as it provides a dump of current wireless settings to the CLI, and it can also be set up to generate specific logs for troubleshooting. Another comprehensive tool is the sysdiagnose tool, which can generate a wide range of logs, although it mostly provides point-in-time information in relation to wireless, similar to wdutil.
To run it in the background and generate logs at /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. For an interactive run (with minimal interaction), execute sudo /usr/bin/sysdiagnose which will trigger a privacy warning. If 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. However, be cautious of the file sizes, which are around 300MB or slightly more.
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