Troubleshoot Common Wifi Router Issues
Understanding Internet Addressing
When it comes to the Internet, there are various types of IP addresses that can be used, such as the Public IPv4 address or the IPv6 address. These addresses can be checked at https://test-ipv6.com/. However, communicating these addresses to non-technical individuals or even referring to MAC addresses can quickly become complex and error-prone. Moreover, obtaining historical data, especially from previous issues, remains a challenge.
Navigating the World Wide Web
Accessing a website like https://shields.net entails contacting a DNS server to translate the URL into an IP address. Your computer and browser include specific information in all web requests, such as the type of browser.
The Significance of Default Gateways
The default gateway is typically automatically configured through DHCP and serves as the point to which your computer sends all its traffic to be routed onwards. The default gateway is usually designated with an address that ends in .1 or .254, depending on the size of the scope. For IPv6, you can refer to how-to-fix-ipv6-connectivity/ for detailed information on how to check this on Mac or Linux.
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 192.168.82.45 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:a7aa:8912:9975:ac5f%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): {150.103.28.155, 112.177.116.157}
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 77:dd:ac:98:7b: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 46:e6:b4:b2:79:79
}
Resolving Issues with Wired and Wireless Connection
When it comes to transmitting data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX Users
Regardless of whether you are running OSX/macOS versions such as 10.11.3, 11.6.4, or 12.0.3, 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 particularly useful, especially for teams that are practicing remote work and embracing the concept of Work From Anywhere (WFA).
Useful Built-in Scripts
For users of OSX/macOS, the sudo wdutil info tool is incredibly helpful as it provides a dump of current wireless related settings to the CLI, and can also be configured to generate specific logs for troubleshooting. Moreover, the sysdiagnose tool can be used to generate a wide range of logs, although most of the information is only available at a specific point in time, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & will run the sysdiagnose tool in the background and create logs in /var/tmp/<blah>.tar.gz for the user. If you prefer to run it interactively, you can execute 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 and use Finder with Cmd+Shift+G to point Finder to the path. Keep in mind that the file sizes are usually around 300MB.
Possibly Helpful Videos
P.S. Tips For Remote Network and Client Support
Digital work requires reliable connectivity. Whether for low latency or regular data streams, Wi-Fi, DNS, and network issues cause teams to lose time and productivity. Even worse is when support teams waste time trying to recreate and isolate issues! See how PanSift saves time, money, and frustration on all sides with instant remote troubleshooting 🏠🏝🛰.
