How To Support Common Wifi Internet Issues
An Explanation of Internet Addressing
When using the Internet, you may receive a Public IPv4 address such as 229.197.87.52 or an IPv6 address like 2000:eb78:438f:8391:8b1f:5597:7438:3b28. Verification of this information can be done at https://test-ipv6.com/. However, for those not well-versed in technology to convey these addresses, or even recognize MAC addresses like c8:ea:a0:a0:e5:bb, mistakes are likely to occur and complexity arises. Furthermore, this method does not provide historical data, particularly for past issues.
Navigating the World Wide Web
Accessing a website such as https://hickle.name initially requires contacting a DNS server to convert the host portion (hickle) combined with the Top Level Domain (name) of the URL into an IP address like 151.203.234.175. Whenever a web request is made, your computer and browser transmit their type, for example: Mozilla/5.0 (Windows; U; Win 9x 4.90; SG; rv:1.9.2.4) Gecko/20101104 Netscape/9.1.0285
Understanding the Significance of Default Gateways
Typically, your default gateway is an address that is automatically configured via DHCP. This could be a default gateway like 192.0.0.231 (though they usually end in .1 or .254 depending on the scope size), and this is the destination where your computer redirects all of its traffic to be routed further. Although a deeper explanation on how-to-fix-ipv6-connectivity/ is offered for IPv6, you can confirm this on Mac or Linux 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 192.0.0.231 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:c461:2982:592:b123%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): {202.176.58.138, 43.94.239.132}
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 c8:ea:a0:a0:e5:bb
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 9e:47:c4:9a:08:69
}
Resolving Connectivity Issues for Wired and Wireless Networks
When it comes to transferring 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
No matter which version of OSX/macOS you are currently using - whether it’s 10.15.7, 11.6.6, or 12.1.6 - there are various tools available for troubleshooting. However, these manual actions and scripts fail to provide a set of correlated values over time. This is where automated remote troubleshooting proves to be particularly advantageous, especially for teams that are transitioning to remote work and embracing a Work From Anywhere (WFA) approach.
Helpful Built-in Scripts
On OSX/macOS, the sudo wdutil info tool is extremely beneficial as it provides a dump of the current wireless settings to the CLI, which can be configured to generate specific logs for troubleshooting. Moreover, the sysdiagnose tool, although primarily point-in-time in relation to wireless, can be used to generate a wide range of logs, making it a more comprehensive option.
To run sysdiagnose in the background and have it write logs to /var/tmp/<blah>.tar.gz, you can use the command sudo nohup /usr/bin/sysdiagnose -u &. Alternatively, running it interactively by using sudo /usr/bin/sysdiagnose will prompt a privacy warning, and the generated logs can be found in the correct location in Finder, in the /var/tmp directory, or accessed through Finder with Cmd+Shift+G. It’s important to keep in mind that the file sizes are approximately 300MB.
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