How Do You Fix Mac Internet

The Functioning of Internet Addressing

When connecting to the Internet, you are assigned a Public IPv4 address such as 101.230.20.116 or an IPv6 address like 2000:195d:b575:d22:c2ae:b0d5:7dbe:b318. You can verify this information by visiting https://test-ipv6.com/. However, relaying these addresses or MAC addresses like af:57:42:3e:50:5f to individuals without technical knowledge can result in errors and complexity. Furthermore, the lack of historical data from past issues doesn’t help.

Navigating the Internet

To access a website like https://hettinger.co, your first point of contact is a DNS server, which translates the host portion (hettinger) along with the Top Level Domain (co) of the URL into an IP address, such as 193.77.183.198. Every time you make a web request, your computer and browser include information about their type, for example
Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)

The Significance of Default Gateways

The default gateway is typically an address that is automatically configured through DHCP. In most cases, you will receive a default gateway like 192.0.0.154 (usually ending in .1 or .254 depending on the scope size), and this is the destination where your computer sends all its outbound traffic. For details on IPv6, you can refer to our comprehensive guide on how-to-fix-ipv6-connectivity/ or perform a check on Mac or Linux by 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  192.0.0.154    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:e1a3:9452:ca32:88b9%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): {189.207.59.101, 60.167.149.250}
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 af:57:42:3e:50:5f
  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 98:a8:bf:71:48:2f
}

Troubleshooting Methods for Wired and Wireless Connections

When it comes to sending data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.

Tips for Apple macOS / OSX Users

Whether you’re running macOS or OSX version 10.15.8, 11.3.2, 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 are embracing remote work and Work From Anywhere (WFA).

Useful Built-in Scripts

A very useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump to the CLI of current wireless related settings and can be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is point-in-time only in relation to wireless, 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, which will give 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. Just be aware of the file sizes, which are about 300MB more or less.

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