How To DiagnOSe Wifi Internet Issues
Understanding IP Addressing
In the realm of the Internet, an individual may be assigned a Public IPv4 address, such as 247.154.88.131, or an IPv6 address, like 2000:27a5:f640:add7:b801:6066:f8c5:50d9. This information can be verified at https://test-ipv6.com/. However, for those who are not technically inclined, attempting to relay or reference these IP addresses, as well as MAC addresses like 91:44:a5:b7:36:57, can be prone to mistakes and quickly become complex. Furthermore, this method does not provide any historical data, especially pertaining to past issues that may have arisen.
Navigating the Internet
When venturing to a website, such as https://mayert.info, the first step is accessing a DNS server to convert the host portion (mayert) combined with the Top Level Domain (info) of the URL into an IP address, such as 214.129.174.123. Interestingly, the computer and browser reveal information about themselves with all web requests, for example: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
Understanding the Role of Default Gateways
The default gateway is typically automatically configured through DHCP. An example of a default gateway might be 172.20.192.209 (although they often end in .1 or .254 based on the scope size), and this is where a computer directs all of its traffic to be routed onward. For a comprehensive exploration of IPv6, visit how-to-fix-ipv6-connectivity/, or perform checks on Mac or Linux with:
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 172.20.192.209 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 fe80:35a3:34da:c42b:147c%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): {253.233.1.69, 93.54.25.223}
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 91:44:a5:b7:36:57
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 c1:de:ff:7e:6b:9e
}
Diagnosing Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you could be utilizing a wired or wireless (Wi-Fi) medium at the physical and data layer.
Effective Troubleshooting for Apple macOS / OSX Users
Irrespective of whether you are using OSX/macOS versions such as 10.14.7, 11.0.3, or 12.3.7, there exists an array of tools for troubleshooting. However, these manual actions and scripts fail to provide a series of correlated values over time. This is where automated remote troubleshooting proves to be invaluable, especially for teams that prioritize remote work and Work From Anywhere (WFA).
Leveraging the Power of Built-in Scripts
A highly useful tool on OSX/macOS is the sudo wdutil info, which provides a CLI dump of current wireless settings and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool offers a more comprehensive approach, generating a wide range of logs, although much of it is only point-in-time in relation to wireless, just like wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (despite the lack of interaction), you can use sudo /usr/bin/sysdiagnose and navigate to the correct location in Finder or use Cmd+Shift+G to point Finder to the path. However, be mindful of the file sizes, which are around 300MB more or less.
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 🏠🏝🛰.
