How To Fix Wifi Connectivity
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 address, such as 63.88.35.178, or an IPv6 address, like 2000:fbfa:298c:48a3:e49a:73f:39f9:2aac. You can verify this information by visiting https://test-ipv6.com/. However, explaining and sharing these addresses, or even mentioning MAC addresses, such as 80:b8:c6:28:80:04, can become prone to errors and quickly become complex. Moreover, it does not provide any historical data, especially when dealing with past issues.
Navigating the World Wide Web
When attempting to access a web page, like https://bednar.info, your computer initially contacts a DNS server to translate the host portion (bednar) combined with the Top Level Domain (info) of the URL into an IP address, such as 243.141.3.146. Your computer and browser also include its type with all web requests, for instance, 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
The default gateway for your network is typically automatically configured via DHCP. This gateway is assigned an IP address, such as 192.168.76.62 (although they usually end in .1 or .254 depending on the size of the scope), and serves as the point to which your computer sends all of its traffic to be routed further. For IPv6, detailed instructions can be found in the article how-to-fix-ipv6-connectivity/, but it can also be verified on Mac or Linux using the following command:
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 192.168.76.62 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 fe80:10fb:5328:3fa:6bd7%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): {130.90.61.204, 61.79.107.217}
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 80:b8:c6:28:80:04
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 e7:21:ed:09:c0:3d
}
Solutions for Resolving Wired and Wireless Issues
When it comes to transmitting data to your router, you might be utilizing a wired or wireless (Wi-Fi) medium at the physical and data layer.
Tips for Troubleshooting on Apple macOS / OSX
Regardless of the version of OSX/macOS you are working on, whether it’s 10.14.3, 11.4.5, or 12.2.1, 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 particularly useful, especially for teams that embrace remote work and Work From Anywhere (WFA).
Pre-Installed Scripts for Assistance
A highly beneficial tool on OSX/macOS is the sudo wdutil info command, which provides a dump of the current wireless settings in the command line interface. It can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool offers a more comprehensive option for generating a wide range of logs, although it mainly captures point-in-time data related to wireless, similar to wdutil.
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 &. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose, but be prepared for 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. Keep in mind that the file sizes are approximately 300MB.
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