How Do You Test Wifi Internet Issues
Functioning of Internet Addressing
When connected to the Internet, you may be assigned a Public IPv4 address such as 119.53.240.165 or an IPv6 address like 2000:1453:c60b:2647:7a22:2745:3c26:1021. This can be confirmed at https://test-ipv6.com/. However, explaining these addresses to non-technical individuals, or even referencing MAC addresses like ed:12:b7:da:3b:27, can be prone to errors and become complex. Furthermore, it does not provide any historical data, particularly regarding past issues.
Navigating the World Wide Web
To access a webpage such as https://walter-gulgowski.io, the first step is to connect to a DNS server to convert the host portion (walter-gulgowski) combined with the Top Level Domain (io) of the URL into an IP address like 147.10.70.8. Your computer and browser include its type with every web request, such as 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 that is automatically configured via DHCP. A typical default gateway appears as 10.165.250.131 (although they usually end in .1 or .254 depending on the scope size) and is responsible for routing all of your computer’s traffic. For IPv6, a detailed explanation is available at how-to-fix-ipv6-connectivity/ but can be verified 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 10.165.250.131 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 fe80:4a8f:ccc6:36d4:d10d%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): {18.151.17.114, 181.115.48.251}
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 ed:12:b7:da:3b:27
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 68:90:cc:86:cd:11
}
Troubleshooting Connectivity Issues
When it comes to establishing a connection, whether wired or wireless, you may encounter issues at the physical and data layers. This can impact the transmission of data to your router, leading to connectivity issues.
Resolving Connectivity Problems on Apple Devices
Regardless of the version of macOS you are using, whether it’s 10.14.9, 11.4.3, or 12.3.3, there are various troubleshooting tools available. However, these manual processes and scripts may not provide a comprehensive overview of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams engaged in remote work and the Work From Anywhere (WFA) approach.
Useful Built-in Scripts
A valuable tool on macOS is the sudo wdutil info command, which provides a dump of current wireless settings to the command line interface. It can also be configured to generate specific logs for troubleshooting purposes. In addition, the sysdiagnose tool offers a more comprehensive option for generating a wide range of logs, although it mainly captures point-in-time wireless data similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will create logs in /var/tmp/<blah>.tar.gz for you. Alternatively, if you prefer to run it interactively, you can use the command sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. When run interactively, it should open Finder in the correct location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G. Keep in mind that the file sizes can be around 300MB.
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