How To Fix Wifi Router Issues
Understanding Internet Addressing
When using the internet, you are assigned a Public IPv4 address, such as 149.65.142.165, or an IPv6 address, like 2000:3340:81df:830f:cae2:4c76:2edd:fec6. The website https://test-ipv6.com/ allows you to verify these addresses. However, communicating these addresses, or even referring to MAC addresses like 16:df:44:04:d1:f5, can be error-prone and complex for those not well-versed in technology. Furthermore, this method does not provide any historical data, particularly when past issues have arisen.
Navigating the World Wide Web
Whenever you want to visit a website, such as https://marvin.net, your first step is to access a DNS server. This server translates the combination of the host portion (marvin) and the Top Level Domain (net) of the URL into an IP address, such as 88.144.184.118. Additionally, your computer and browser provides its type with all web requests, for example:
Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0
The Significance of Default Gateways
The default gateway is typically an address configured automatically via DHCP. You receive a default gateway, such as 192.168.117.100 (although they usually end in .1 or .254 depending on the scope size), and this is the point where your computer forwards all its traffic to be routed onward. For IPv6, comprehensive instructions can be found in our blog post how-to-fix-ipv6-connectivity/. On Mac or Linux, you can verify this with:
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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 192.168.117.100 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 fe80:7e94:2382:e983:7732%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): {152.87.67.208, 62.133.219.115}
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 16:df:44:04:d1:f5
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 f0:09:a3:00:31:f3
}
Resolving Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium, operating at the physical and data layer.
Solutions for Apple macOS / OSX Users
Regardless of whether you are using OSX or macOS versions such as 10.14.5, 11.5.4, or 12.2.6, there is a variety of troubleshooting tools available. However, these manual processes and scripts do not provide a set of interconnected values over a period of time. In such cases, automated remote troubleshooting comes to the forefront, especially for teams that adopt remote work and Work From Anywhere (WFA).
Utilizing Pre-installed Scripts for Assistance
One useful tool for OSX/macOS users is the sudo wdutil info, which generates a dump of the current wireless settings to the CLI and can also produce specific logs for troubleshooting purposes. Furthermore, the sysdiagnose tool offers a more comprehensive range of logs, although most of them are only related to wireless settings 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 (even though 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. However, you can also navigate to /var/tmp using the Cmd+Shift+G command in Finder, bearing in mind that the file sizes are around 300MB.
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