How Can I Fix MacOS Issues
Understanding Internet Addressing
When using the Internet, you are assigned a Public IPv4 or IPv6 address, such as 1.74.186.96 or 2000:f2a5:c57e:c0d9:10b0:14fc:49fb:b621. Verification can be done on https://test-ipv6.com/. Communicating, or even referencing MAC addresses like dd:d7:cf:32:64:ff, can be challenging for non-technical individuals and can quickly become complex. Moreover, this method lacks historical data, particularly during previous issues.
Navigating the World Wide Web
In order to access a website like https://ward.com, you initially send a request to a DNS server to translate the host (ward) and the Top Level Domain (com) of the URL into its corresponding IP address, such as 226.185.130.85. Your computer and browser include their specifications in all web requests, such as Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16.
Significance of Default Gateways
The default gateway is typically an address automatically configured via DHCP, such as 10.170.34.221 (commonly ending in .1 or .254, depending on the scope size). This is the point where your computer directs all its outgoing traffic for further routing. For IPv6, a detailed explanation can be found at how-to-fix-ipv6-connectivity/, and for Mac or Linux systems, you can verify this using:
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 10.170.34.221 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:ebc8:c22e:6995:a492%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): {127.142.52.132, 140.36.99.201}
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 dd:d7:cf:32:64:ff
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 1b:a4:c4:21:ff:f5
}
Resolving Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you may be using either 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 10.13.2, 11.5.2, or 12.1.3, there are various troubleshooting tools available. However, these manual methods and scripts do not provide a consistent set of correlated values over time. This is where automated remote troubleshooting becomes invaluable, particularly for teams that adopt remote work and the Work From Anywhere (WFA) approach.
Useful Built-in Scripts
A highly useful tool on OSX/macOS is 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 offers a more comprehensive option for generating a wide range of logs, although much of it is related to wireless settings and is only point-in-time data, similar to wdutil.
To run it in the background and generate logs in /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, use sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. If not run in the background, it should open Finder in the correct location or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to locate the files. Keep in mind that the file sizes are approximately 300MB.
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