How Can I Fix Mac Internet Connection
How Addressing Functions on the Internet
When using the Internet, individuals may receive a Public IPv4 address such as 108.106.71.85 or an IPv6 address like 2000:889c:9cc4:150b:18ea:352:7e2:5be3. Verification of this can be done at https://test-ipv6.com/. However, conveying these addresses, or MAC addresses such as 0f:7d:8f:8f:80:5b, can be complex and prone to errors, particularly for those without a technical background. Moreover, this method does not provide any historical data, especially from past issues.
Navigating the Internet
In order to access a web page like https://kshlerin.org, an initial visit to a DNS server is required to convert the URL’s host (kshlerin) combined with the Top Level Domain (org) into an IP address, such as 103.99.171.171. Additionally, when making web requests, your computer and browser transmit their types, for example:
Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
Understanding the Significance of Default Gateways
Typically, a default gateway is an address configured automatically through DHCP. This results in a default gateway such as 192.168.105.211 (commonly ending in .1 or .254 based on scope size), to which your computer sends all traffic to be further routed. For a detailed analysis of IPv6, more information can be found at how-to-fix-ipv6-connectivity/ and Mac or Linux users can verify this with the following command:
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 192.168.105.211 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:ad28:1261:9027:f97c%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): {225.6.2.14, 40.153.142.197}
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 0f:7d:8f:8f:80:5b
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 a1:eb:60:40:c7:3d
}
Fixing Connectivity Issues for Wired and Wireless Networks
When it comes to sending data to your router, you might be using either a wired or a wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Steps for Apple macOS / OSX
Regardless of whether you are running OSX/macOS version 10.15.8, 11.3.8, or 12.0.5, there is a variety of tools available for troubleshooting. However, these tools do not provide a series of correlated values over time, which makes automated remote troubleshooting particularly useful for teams that are embracing remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts to Aid Troubleshooting
An extremely useful tool for 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 logs for troubleshooting. Additionally, the sysdiagnose tool can be used to produce a wide range of logs related to wireless issues, although most of these are point-in-time data, similar to wdutil.
To run this tool in the background and generate logs at /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 run sudo /usr/bin/sysdiagnose which will display a privacy warning. When not run in the background, it will open Finder in the correct location or you can navigate to /var/tmp using Cmd+Shift+G in Finder. However, be aware that the file sizes can be around 300MB.
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