How Can I Fix Apple Connectivity
Understanding Internet Protocol Addressing
When using the Internet, it is common to have a Public IPv4 address such as 17.170.50.139 or an IPv6 address like 2000:d793:47be:bb58:a412:7730:5002:c465. These can be verified at https://test-ipv6.com/. However, explaining and communicating these addresses, as well as MAC addresses like 81:5e:19:88:29:85, can be challenging for non-technical individuals, and may lead to errors. Furthermore, it does not provide historical data, especially for past issues.
Navigating the World Wide Web
When accessing a website like https://erdman.name, the process begins with accessing a DNS server to convert the combination of the host portion (erdman) and the Top Level Domain (name) of the URL into an IP address such as 170.252.82.38. Your computer and browser include its type in all web requests, 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
Understanding the Significance of Default Gateways
The default gateway is typically an auto-configured address through DHCP, such as 10.229.106.185 (commonly ending in .1 or .254 based on the scope size). This is where your computer sends all its traffic to be routed onwards. For IPv6, an in-depth guide can be found at how-to-fix-ipv6-connectivity/, and you can verify on Mac or Linux with:
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 10.229.106.185 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:c554:9583:9f5:ca09%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): {63.245.254.134, 163.190.74.255}
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 81:5e:19:88:29:85
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 ae:a0:dd:44:fb:df
}
Resolve Issues with Wired and Wireless Connections
When 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
No matter which version of macOS or OSX you are using, whether it’s 10.11.2, 11.3.4, or 12.0.9, 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 essential, especially for teams that embrace remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
A very useful tool on OSX/macOS is the sudo wdutil info, which provides a dump of current wireless settings to the CLI, and can 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 at a specific point in time, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs in /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (although there is minimal interaction), you can run sudo /usr/bin/sysdiagnose, which will prompt 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 or use the path in Finder. Keep in mind that the file sizes are approximately 300MB.
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