How Do You Fix MacOS Internet Connection
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 or IPv6 address. Checking this address can be done from a website like https://test-ipv6.com/. However, conveying and communicating these addresses, including MAC addresses, can be complicated, especially for those who are not tech-savvy. It also does not provide any historical data.
Navigating the World Wide Web
Accessing a website, such as https://gerlach-tromp.org, involves reaching out to a DNS server to translate the URL’s host and Top Level Domain to an IP address. Additionally, your computer and browser send specific type information with all web requests.
The Significance of Default Gateways
Your default gateway is typically assigned automatically through DHCP and serves as the path through which your computer sends its traffic. The default gateway often ends in .1 or .254, depending on the scope size, and is crucial for routing all traffic onwards. For IPv6, detailed instructions can be found on how-to-fix-ipv6-connectivity/. It is also possible to check this on Mac or Linux.
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 172.20.204.72 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 fe80:2e6a:2522:6618:53bf%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): {5.16.47.156, 120.107.146.53}
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 e9:cc:b4:89:02:a0
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 80:ac:70:9f:d3:fb
}
Resolve Connectivity Issues with Wired or Wireless Networks
When it comes to transmitting data to your router, you might be using a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX
Regardless of whether you are running OSX/macOS version 10.14.4, 11.2.9, or 12.2.7, there are various tools available for resolving connectivity issues. However, these manual troubleshooting actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that have embraced remote work and Work From Anywhere (WFA).
Utilize These Built-in Scripts
One powerful tool on OSX/macOS is the sudo wdutil info, 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 comprehensive set of logs, although much of it is only relevant at a specific point in time, similar to wdutil.
To run sysdiagnose in the background and 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, but be aware of the large file sizes of about 300MB.
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