Understand Wifi Internet Issues
Understanding the Function of Internet Addressing
When using the internet, you are assigned a Public IPv4 address, such as 1.209.74.95, or an IPv6 address, such as 2000:6620:6379:fad0:b33c:8e60:35a3:403f. This information can be verified using https://test-ipv6.com/. However, attempting to convey these addresses or even referencing MAC addresses like ab:d8:16:79:30:89 to individuals who are not well-versed in technology can be prone to mistakes and quickly become complex. Furthermore, it fails to provide any historical data, particularly when previous issues occurred.
Navigating the World Wide Web
When trying to traverse to a webpage, such as https://douglas.biz, the first step involves accessing a DNS server, which in turn translates the host portion (douglas) combined with the Top Level Domain (biz) of the URL into an IP address, such as 248.176.174.166. Moreover, your computer and browser send its type with every web request, 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 Significance of Default Gateways
Typically, your default gateway is an automatically configured address via DHCP, resulting in a default gateway like 192.0.0.17 (commonly ending in .1 or .254, depending on the scope size). This is the location where your computer forwards all its traffic to be routed onwards. For IPv6, detailed instructions are available in our article how-to-fix-ipv6-connectivity/, but it can be checked 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 192.0.0.17 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 fe80:2e14:b10d:3c8b:a213%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): {244.51.173.77, 204.126.2.182}
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 ab:d8:16:79:30:89
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 6f:8e:42:24:4e:bc
}
Resolving Connectivity Issues for Wired and Wireless Networks
When it comes to transmitting data to your router, you have the option of using a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX Users
Regardless of whether you are running OSX/macOS 10.12.2, 11.3.7, or 12.2.1, there are various troubleshooting tools available. However, these manual actions and scripts fall short in providing 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) practices.
Handy Built-in Scripts for Assistance
One tool that proves to be very helpful on OSX/macOS is sudo wdutil info, which provides a dump of the current wireless settings to the CLI and can also be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of the information is only relevant at a specific point in time, similar to wdutil.
To run sysdiagnose in the background and generate logs in /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 the command sudo /usr/bin/sysdiagnose, which will prompt 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, but be cautious of the large file sizes, usually around 300MB.
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