How Do You Test Common Wifi Internet Issues
Functioning of Internet Addressing
When using the Internet, individuals are assigned either a Public IPv4 address, such as 231.250.182.74, or an IPv6 address, like 2000:5f94:d67:763a:142:fb5c:2f84:5f7d. The verification can be done at https://test-ipv6.com/. However, for those who are not tech-savvy, conveying these addresses and MAC addresses, such as 24:68:0d:30:0f:6a, can be prone to errors and become complex. Furthermore, this method lacks historical data, particularly when dealing with past issues.
Navigating the World Wide Web
When attempting to access a website like https://halvorson.com, the first step involves contacting a DNS server to convert the host name (halvorson) combined with the Top Level Domain (com) of the URL into an IP address like 169.100.38.229. Every web request sent out by your computer and browser includes its type, for instance Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
Understanding the Significance of Default Gateways
Typically, your default gateway is an automatically assigned address through the DHCP. This address, such as 172.21.17.130 (usually ending in .1 or .254 based on the scope size), is where all traffic from your computer is forwarded. For a detailed breakdown of IPv6, visit how-to-fix-ipv6-connectivity/. On Mac or Linux, it can be verified 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 172.21.17.130 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 fe80:5224:67e9:f007:abf9%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): {241.183.107.104, 157.23.25.185}
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 24:68:0d:30:0f:6a
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 55:fd:29:d3:6b:6c
}
Resolving Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you may rely on either a wired or a wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting on Apple macOS / OSX Systems
For all versions of OSX/macOS, including 10.14.6, 11.6.4, or 12.2.7, a variety of tools are available for resolving issues. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that have embraced remote work and Work From Anywhere (WFA).
Utilizing Pre-installed Scripts for Assistance
One particularly useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI and can also be configured to generate specific troubleshooting logs. Furthermore, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only relevant to wireless at a specific point in time, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & will execute it in the background and write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively (even though there is minimal interaction), you can execute sudo /usr/bin/sysdiagnose and it will display a privacy warning. When 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 mindful of the file sizes, which can be around 300MB.
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