How To Fix Wifi No Access
The Functioning of Internet Addressing
When accessing the Internet, you may be assigned a Public IPv4 address, such as 205.61.238.250, or an IPv6 address, like 2000:802e:6780:4196:72e:49a2:a817:56b0. The verification of this can be done through https://test-ipv6.com/. However, for individuals who are not technologically savvy, attempting to communicate these addresses, or even know the MAC addresses like f0:8d:81:ce:03:4a, can be prone to errors and become complex. Furthermore, this process does not provide any historical data, especially during past issues.
Navigating the Internet
Accessing a webpage, such as https://turcotte.info, initially requires accessing a DNS server to translate the host part, “turcotte,” combined with the Top-Level Domain, “info,” of the URL into an IP address, such as 184.196.106.0. Your computer and browser transmit their types with 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
Understanding the Significance of Default Gateways
Typically, your default gateway is an automatically configured address via DHCP, such as 172.27.233.77 (usually ending in .1 or .254 based on scope size). This is where your computer directs all its traffic for further routing. A detailed guide on how to fix IPv6 connectivity can be found on how-to-fix-ipv6-connectivity/, and you can check on Mac or Linux by using:
ip -6 route
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 172.27.233.77 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:c1c6:d5bd:e140:6eaf%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): {87.65.131.216, 165.15.31.120}
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 f0:8d:81:ce:03:4a
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 ab:70:ae:6f:ba:f0
}
Resolving Issues with Wired and Wireless Connections
When it comes to transferring data at the physical and data layer, there are two options: wired or wireless (Wi-Fi) mediums. Both have their own set of challenges, so it’s important to troubleshoot and fix any problems that may arise.
Tips for Apple macOS / OSX Users
No matter which version of OSX/macOS you’re using - whether it’s 10.12.4, 11.3.2, or 12.1.2 - there are several tools available for troubleshooting connectivity issues. While manual actions and scripts can help, they don’t always provide a comprehensive view of the problem over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that work remotely or have a “Work From Anywhere” (WFA) policy.
Useful Built-in Scripts
One valuable tool for OSX/macOS users is the sudo wdutil info command, which displays current wireless settings and can also generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool is more comprehensive and can generate a wide range of logs related to connectivity issues, although much of the information is only relevant at a specific point in time, similar to wdutil.
To run sysdiagnose in the background and save the logs to /var/tmp/<blah>.tar.gz, you can use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run sysdiagnose interactively, you can run sudo /usr/bin/sysdiagnose, but be aware that the file sizes can be 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 🏠🏝🛰.
