Troubleshoot MacOS Internet Connection

Understanding the Fundamentals of Internet Addressing When using the Internet, you are assigned a Public IPv4 address or an IPv6 address. You can verify your address using a tool like https://test-ipv6.com/. However, communicating these addresses, or even MAC addresses, can be complex for those who are not technologically savvy. Understanding the Fundamentals of Internet Addressing When using the Internet, you are assigned a Public IPv4 address or an IPv6 address. You can verify your address using a tool like https://test-ipv6.com/. However, communicating these addresses, or even MAC addresses, can be complex for those who are not technologically savvy.

Understanding the Fundamentals of Internet Addressing

When using the Internet, you are assigned a Public IPv4 address or an IPv6 address. You can verify your address using a tool like https://test-ipv6.com/. However, communicating these addresses, or even MAC addresses, can be complex for those who are not technologically savvy. Moreover, this method does not provide any historical data.

Accessing a web page, such as https://lesch.net, involves first accessing a DNS server to translate the URL into an IP address. All web requests sent from your computer and browser include the type, such as
Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0

Understanding the Significance of Default Gateways

Your default gateway is typically an address automatically configured via DHCP. This is where your computer sends all its traffic to be routed onwards. For IPv6, guidance on how to check on Mac or Linux is available at how-to-fix-ipv6-connectivity/

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  10.9.176.209    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   fe80:20b1:625:c18c:5000%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): {69.49.169.42, 102.246.132.83}
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 13:93:11:0b:0a:d1
  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 a0:15:28:df:8a:29
}

Troubleshooting Tips for Wired and Wireless Connectivity

When it comes to sending data to your router, you may be using a wired or wireless (Wi-Fi) medium at the physical and data layer.

Solutions for Apple macOS / OSX Issues

Regardless of the version of OSX/macOS you are using, whether it’s 10.15.8, 11.6.1, or 12.0.5, 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 valuable, especially for teams that adopt remote work and Work From Anywhere (WFA) practices.

Useful Built-in Scripts

An essential tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings to the CLI, and can also be configured to generate specific troubleshooting logs. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only relevant to wireless settings, similar to wdutil.

To run sysdiagnose in the background and generate logs at /var/tmp/<blah>.tar.gz, you can use the following command: sudo nohup /usr/bin/sysdiagnose -u &. For an interactive experience, you can run sudo /usr/bin/sysdiagnose and it will provide a privacy warning. If not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp using Cmd+Shift+G in Finder. Keep in mind that the file sizes can be around 300MB.

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P.S. PanSift Tip For Work From Anywhere Support

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