How To Fix Common Wifi Internet Issues
Understanding Internet Address Structure
When you connect to the Internet, you are assigned either a Public IPv4 address, such as 50.48.92.35, or an IPv6 address, such as 2000:32b:668b:2005:5faa:d93a:7554:cad5. You can verify this information at https://test-ipv6.com/. However, explaining or communicating these addresses, as well as MAC addresses like 01:95:35:ba:f2:0a, can be prone to errors and complexity. Moreover, it does not offer any historical data, particularly for past issues.
Navigating Websites
When you want to access a website like https://oconnell.org, you initially contact a DNS server to convert the combination of the host (oconnell) and the Top Level Domain (org) of the URL into an IP address, such as 140.217.129.242. Your computer and browser include their types in 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.
Significance of Default Gateways
Your default gateway is typically an automatically assigned address via DHCP and is likely to end in .1 or .254, depending on the scope. This is where your computer directs all its traffic for further routing. For IPv6, you can learn more at how-to-fix-ipv6-connectivity/ and check 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 172.23.212.154 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 fe80:83f:cce1:5eca:c5d3%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): {71.63.65.65, 76.55.176.144}
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 01:95:35:ba:f2:0a
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 01:75:56:01:40:78
}
Fixing Connectivity Issues for Wired and Wireless Networks
When it comes to transmitting data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX Users
No matter which version of OSX/macOS you’re using - whether it’s 10.13.8, 11.6.2, or 12.3.9, there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes important, especially for teams that embrace remote work and Work From Anywhere (WFA).
Useful Built-in Scripts for Troubleshooting
A very useful tool on OSX/macOS is the sudo wdutil info, which provides a dump to the CLI of current wireless related settings and can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is point-in-time only in relation to wireless, similar to wdutil.
To run sysdiagnose in the background and write logs to /var/tmp/<blah>.tar.gz, you can use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose, which will give 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 cautious of the file sizes, which are approximately 300MB.
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