How To Troubleshoot MacOS Internet Connection

Understanding the Functionality of Internet Addressing When on the Internet, you are assigned either a Public IPv4 address, such as 199.91.197.135, or an IPv6 address, like 2000:c0d4:b280:1f47:beb:512e:49a4:306a. Verification of this information can be performed at https://test-ipv6.com/. However, for individuals not well-versed in technology, attempting to communicate or identify addresses, such as MAC addresses, can be prone to errors and complications. Understanding the Functionality of Internet Addressing When on the Internet, you are assigned either a Public IPv4 address, such as 199.91.197.135, or an IPv6 address, like 2000:c0d4:b280:1f47:beb:512e:49a4:306a. Verification of this information can be performed at https://test-ipv6.com/. However, for individuals not well-versed in technology, attempting to communicate or identify addresses, such as MAC addresses, can be prone to errors and complications.

Understanding the Functionality of Internet Addressing

When on the Internet, you are assigned either a Public IPv4 address, such as 199.91.197.135, or an IPv6 address, like 2000:c0d4:b280:1f47:beb:512e:49a4:306a. Verification of this information can be performed at https://test-ipv6.com/. However, for individuals not well-versed in technology, attempting to communicate or identify addresses, such as MAC addresses, can be prone to errors and complications. Additionally, this method does not provide any historical data, particularly from previous issues.

In order to access a website, such as https://purdy.co, the first step involves consulting a DNS server to convert the host portion (purdy) combined with the Top Level Domain (co) of the URL into an IP address, such as 170.131.197.55. Furthermore, your computer and browser transmit its type 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

The Significance of Default Gateways

Typically, your default gateway is an automatically configured address via DHCP, resulting in a default gateway like 172.16.156.25 (usually ending in .1 or .254, depending on the scope size). This is where your computer forwards all its traffic to be routed onwards. For IPv6, a comprehensive overview is available at how-to-fix-ipv6-connectivity/, but you can verify on Mac or Linux using the 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  172.16.156.25    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   fe80:68b2:c13a:ea1b:2c9a%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): {180.140.118.223, 21.187.155.116}
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 62:1a:d4:19:2b:fa
  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 48:4f:dd:f2:6a:21
}

Resolving Connection Issues for Wired or Wireless Networks

In your network setup, whether using a wired or wireless (Wi-Fi) medium, you may encounter issues when sending data to your router.

Troubleshooting on Apple macOS / OSX

Regardless of the version of OSX/macOS you are running, be it 10.14.5, 11.1.7, or 12.0.3, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time. Therefore, automated remote troubleshooting becomes invaluable, particularly for teams that embrace remote work and Work From Anywhere (WFA).

Utilizing Built-in Scripts for Assistance

An extremely useful tool on OSX/macOS is the sudo wdutil info, which provides a dump of current wireless-related settings to the CLI and 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 related to wireless issues, although much of it is only point-in-time data, similar to wdutil.

Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can execute sudo /usr/bin/sysdiagnose, which will provide 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. It’s important to note that the file sizes are approximately 300MB.

Possibly Helpful Videos

Video Title Channel
Spotlight on Spotlight - Hands-On Mac 7 Hands-On Mac
Securing macOS Big Sur Hands-On Mac
On the Road to Big Sur 2 - Compatibility Hands-On Mac
Mac Activity Monitor - How to Troubleshoot Your Mac Hands-On Mac
Secret Mac Boot Commands - Mac Boot Key Combinations Hands-On Mac
Table 1.0 - Video Help



P.S. PanSift Tip For Work From Anywhere Support

Digital work requires reliable connectivity for voice, video, and data. Inevitable Wi-Fi, network, and system issues cause teams to lose time and productivity, or worse, to miss out on opportunities. Whether working from home, a shared space, or an office, and irrespective of the network being managed or unmanaged, forward thinking technical teams embrace smarter tools to save their users and clients time and money! See how PanSift provides instant remote troubleshooting, irrespective of location 🏠🏝🛰.

Design Benefits + 2 Free Agents


Rapid Digital Experience Monitoring for teams and tribes!

Instant Agent

2 x free macOS agents

Live Demo

No registration, immediate live demo!