How Can I Fix Common Wifi Internet Issues
Understanding How Internet Addressing Functions
When using the Internet, you will receive a Public IPv4 address such as 19.34.37.226 or an IPv6 address like 2000:df31:17f4:b5b5:e6e:20b3:4435:b4d1. You can verify this by visiting https://test-ipv6.com/. However, attempting to convey these addresses to non-technical individuals or even mentioning MAC addresses like 91:18:5f:f0:d7:c9 can quickly become complex and error-prone. Moreover, this does not provide any historical data, especially regarding past issues.
Navigating the Internet
When navigating to a website such as https://trantow.org, your first step is to access a DNS server, which will translate the host portion (trantow) combined with the Top Level Domain (org) of the URL into an IP address, such as 131.88.196.11. Every web request from your computer and browser includes its type, for example: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36
Understanding the Significance of Default Gateways
The default gateway is typically an address that is automatically configured via DHCP. You will receive a default gateway such as 192.168.68.203 (although they normally end in .1 or .254 based on the scope size), and this is where your computer directs all its traffic to be routed onwards. For IPv6, a comprehensive guide on how-to-fix-ipv6-connectivity/ is available, but you can also check on Mac or Linux using 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 192.168.68.203 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 fe80:4ffb:4417:5436:7470%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): {239.249.64.135, 88.146.253.171}
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 91:18:5f:f0:d7:c9
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 40:29:79:61:99:65
}
Resolving Connectivity Issues for Wired and Wireless Networks
When it comes to transferring data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Tips for Addressing Problems on Apple macOS / OSX Systems
Regardless of whether you are running OSX/macOS versions such as 10.15.7, 11.2.7, or 12.2.2, there are various troubleshooting tools available. However, the manual actions and scripts provided do not offer a set of correlated values over time. This is where automated remote troubleshooting becomes valuable, particularly for teams that embrace remote work and Work From Anywhere (WFA).
Pre-installed Scripts for Assistance
An extremely useful tool on OSX/macOS is sudo wdutil info, which provides a dump of the current wireless settings to the CLI, and can also be configured to generate specific troubleshooting logs. Furthermore, the sysdiagnose tool can be used to produce a wide range of logs, although much of it is only relevant to wireless at specific points in time, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will create logs in /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (even though there is minimal interaction), you can runsudo /usr/bin/sysdiagnose, which will display a privacy warning. When not run in the background, it should open Finder in the correct location, and you can navigate to /var/tmp or use Finder with Cmd+Shift+G to locate the path. However, be cautious of the large file sizes, which are typically around 300MB.
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