How To Fix OSX Internet Connection
Understanding IP Addresses
When you’re using the Internet, you are assigned an IPv4 address, such as 34.70.247.229, or an IPv6 address, like 2000:27ce:3517:fad2:a84c:85f4:6600:5ece. You can verify this information at https://test-ipv6.com/. However, conveying these addresses to those who are not tech-savvy, or discussing MAC addresses like 66:7d:93:9e:f3:b8, can become complicated and error-prone. Moreover, this method does not provide any historical data.
Navigating the World Wide Web
When you want to visit a website, such as https://mraz.org, your first step is to access a DNS server to convert the host portion (mraz) combined with the Top Level Domain (org) of the URL into an IP address, like 82.135.184.182. Each web request from your computer and browser is accompanied by its type, for example: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
The Significance of Default Gateways
Your default gateway is typically an address that is automatically configured via DHCP. It looks something like 192.168.28.94 (usually ending in .1 or .254 depending on the scope size), and serves as the point where your computer sends all of its traffic to be routed onwards. For a detailed guide on IPv6, you can reference how-to-fix-ipv6-connectivity/, or follow these steps 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 192.168.28.94 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 fe80:55bc:9aa3:cff8:a0ff%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): {110.144.87.246, 106.86.9.169}
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 66:7d:93:9e:f3:b8
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 39:a0:ea:7c:05:e5
}
Fixing Connectivity Issues for Wired and Wireless Networks
When it comes to transmitting data to your router, you might be using a wired connection or a wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Solutions for macOS / OSX Devices
Regardless of whether you are using OSX or macOS versions such as 10.12.3, 11.4.3, or 12.3.4, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes crucial, especially for remote work and Work From Anywhere (WFA) teams.
Useful Built-in Scripts
One of the helpful tools on OSX/macOS is the sudo wdutil info command, 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 generate a wide range of logs, although much of it is only relevant to wireless issues just like wdutil.
To run the sysdiagnose tool in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, use the command sudo /usr/bin/sysdiagnose, keeping in mind that the file sizes can be around 300MB.
Possibly Helpful Videos
P.S. Tips For Remote Network and Client Support
Digital work requires reliable connectivity. Whether for low latency or regular data streams, Wi-Fi, DNS, and network issues cause teams to lose time and productivity. Even worse is when support teams waste time trying to recreate and isolate issues! See how PanSift saves time, money, and frustration on all sides with instant remote troubleshooting 🏠🏝🛰.
