How Can I Troubleshoot MacOS Internet Connection
Understanding the Functioning of Internet Addressing
When using the internet, you may receive a Public IPv4 address, such as 186.30.145.25, or an IPv6 address, such as 2000:f5e4:246:2b50:3bcb:98e:7b54:350a. It is possible to verify this information by visiting https://test-ipv6.com/. However, conveying these addresses to those unfamiliar with technology, or even mentioning MAC addresses like cd:d7:7a:34:5c:35, can lead to errors and complexity. Moreover, this method does not provide any historical data, particularly regarding past issues.
Navigating the Internet
In order to reach a webpage, such as https://wisoky.com, you initially connect to a DNS server to convert the combination of the host portion (wisoky) and the Top Level Domain (com) of the URL into an IP address, such as 86.35.218.224. The computer and browser include their information with every web request, for example: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A
Significance of Default Gateways
Typically, your default gateway is an automatically assigned address through DHCP. The default gateway, such as 192.168.136.27 (usually ending in .1 or .254 based on the scope size), is where your computer directs all traffic to be routed. For IPv6, a comprehensive guide is available on how-to-fix-ipv6-connectivity/, and you can verify this 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 192.168.136.27 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:abed:71f7:15ef:b86a%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): {86.67.22.237, 101.184.49.182}
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 cd:d7:7a:34:5c:35
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 f0:d2:0c:b5:37:b8
}
Repairing Connectivity Issues with Wired and Wireless Networks
When it comes to transmitting data to your router, you might be utilizing either a wired or wireless (Wi-Fi) connection at the physical and data layer.
Troubleshooting Techniques for Apple’s macOS / OSX Operating Systems
Regardless of whether you are running OSX or macOS, whether it’s version 10.12.7, 11.6.5, or 12.1.4, there are a variety of troubleshooting tools available. However, these manual troubleshooting actions and scripts do not provide a set of correlated values over a period of time, which is where automated remote troubleshooting becomes valuable. This is particularly beneficial for teams that have adopted remote work and a Work From Anywhere (WFA) policy.
Utilizing Pre-Installed Scripts for Assistance
One valuable tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the command line interface and can also be configured to generate specific logs for troubleshooting purposes. In addition, the sysdiagnose tool can be used to produce a wide range of logs, although much of it is only relevant to the wireless connection at a specific point in time, 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 the command sudo /usr/bin/sysdiagnose, although it will display a privacy warning. Running it in the background should open Finder in the correct location, or you can navigate to /var/tmp, or use Finder with Cmd+Shift+G to navigate to the path. However, be aware that the file sizes can be around 300MB more or less.
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 🏠🏝🛰.
