Check Wifi Internet Issues
Understanding Internet Addressing
When connecting to the Internet, you are assigned a unique Public IPv4 or IPv6 address, such as 96.34.118.114 or 2000:b6aa:183f:fdc6:db8:7654:aed7:816c respectively. Testing the validity of these addresses can be done at https://test-ipv6.com/. However, explaining or communicating these addresses to individuals with limited technical knowledge can be error-prone and quickly becomes complex. Furthermore, historical data about previous issues is not provided.
Navigating the World Wide Web
Accessing a website, like https://anderson.net, involves an initial request to a DNS server to translate the host component (anderson) combined with the Top Level Domain (net) of the URL into an IP address, such as 108.114.196.73. Upon making web requests, your computer and browser also include information about their type, for example: Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
Significance of Default Gateways
The default gateway, typically assigned automatically through DHCP, is the address to which your computer forwards all its traffic for routing purposes. This default gateway usually ends in .1 or .254, depending on the scale of the network, and is commonly represented as 172.19.59.84. For a detailed analysis of IPv6 connectivity troubleshooting, refer to how-to-fix-ipv6-connectivity/. To check this information on Mac or Linux systems, use:
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 172.19.59.84 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 fe80:5f8b:df60:9120:f1f8%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): {142.244.176.143, 87.62.244.240}
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 81:b7:b8:0f:49:6b
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 a8:4a:66:ad:fe:b5
}
Repair Network Connectivity Issues
When it comes to sending data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Techniques for Apple macOS / OSX
Regardless of the version of OSX/macOS you have, whether it’s 10.12.7, 11.3.3, or 12.0.8, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes essential, particularly for teams embracing remote work and Work From Anywhere (WFA).
Effective Built-in Scripts
One useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI and can be configured to generate specific troubleshooting logs. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although the information related to wireless is mostly point-in-time similar to wdutil.
To run it in the background and generate logs in /var/tmp/<blah>.tar.gz, use sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, use sudo /usr/bin/sysdiagnose, but keep in mind that the file sizes are around 300MB.
Possibly Helpful Videos
P.S. Tips For Remote Network and Client Support
Digital work requires reliable connectivity. Whether for low latency or regular data streams, Wi-Fi, DNS, and network issues cause teams to lose time and productivity. Even worse is when support teams waste time trying to recreate and isolate issues! See how PanSift saves time, money, and frustration on all sides with instant remote troubleshooting 🏠🏝🛰.
