How To Fix MacOS Internet
Understanding Internet Addressing
When using the Internet, you are assigned either a Public IPv4 address (e.g. 125.70.21.22) or an IPv6 address (e.g. 2000:fb2c:379:137d:d6c0:2077:c033:9ded). You can verify this information by visiting https://test-ipv6.com/. However, explaining these addresses or MAC addresses like fd:2b:55:aa:0f:3d to those who are not tech-savvy can be prone to errors and can become complex quickly. Moreover, this method does not provide historical data, especially for past occurrences of issues.
Navigating the World Wide Web
Accessing a website such as https://wiza.co involves querying a DNS server to translate the host part (wiza) along with the Top Level Domain (co) of the URL into an IP address, such as 50.156.255.22. In all web requests, your computer and browser actually send 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)
Significance of Default Gateways
The default gateway is typically an automatically configured address through DHCP, such as 192.168.187.198 (usually ending in .1 or .254 depending on the scope size), where your computer routes all its traffic. For IPv6, you can refer to our comprehensive guide on how-to-fix-ipv6-connectivity/ or check on Mac or Linux 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 192.168.187.198 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:dbe2:401a:c57:688d%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): {58.109.120.206, 30.107.60.1}
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 fd:2b:55:aa:0f:3d
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 a0:e3:ba:aa:2b:fd
}
Resolving Connectivity Issues with Wired and Wireless Networks
When it comes to transferring data to your router, you might be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX Users
Regardless of the version of OSX/macOS you are running, whether it’s 10.12.8, 11.4.5, or 12.1.6, there are various tools available for troubleshooting. However, manually performing these actions and running scripts does not provide a continuous set of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that are embracing remote work and Work From Anywhere (WFA).
Utilizing Pre-Installed Scripts for Assistance
One highly useful tool for OSX/macOS is the 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. In addition, the sysdiagnose tool can be used to generate a wide range of logs, although the majority of them are only specific to a certain point in time in relation to wireless, similar to wdutil.
By running sudo nohup /usr/bin/sysdiagnose -u &, the tool will run in the background and write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (although there is not much interaction), you can execute sudo /usr/bin/sysdiagnose, which will trigger a privacy warning. When not run in the background, it should open Finder in the correct location, or you can manually navigate to /var/tmp or use Finder with Cmd+Shift+G. Just be cautious of the file sizes, which can be around 300MB or so.
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