How Can I Support Wifi Router Issues
Explanation of Internet Addressing
When using the Internet, you are assigned a Public IPv4 address, such as 216.6.239.234, or an IPv6 address, such as 2000:66cc:22bb:e359:49c0:cec9:b74a:fd01. This can be verified by visiting https://test-ipv6.com/. However, for those who are not technically inclined, attempting to convey or remember these addresses, or even referring to MAC addresses like 20:5c:7b:3d:03:be, can be prone to errors and quickly become complex. Furthermore, this method does not provide any historical data, especially for past issues.
Navigating the World Wide Web
To access a website, such as https://koss.name, you first connect to a DNS server to translate the host part (koss) combined with the Top Level Domain (name) of the URL into an IP address, such as 150.232.42.215. Whenever you access a website, your computer and browser send their types along with the web requests, for example: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A
Significance of Default Gateways
A default gateway is typically an automatically assigned address via DHCP, such as 10.47.118.108 (usually ending in .1 or .254 depending on the scope size). This is the location where your computer sends all its traffic to be forwarded. For IPv6, detailed instructions can be found at how-to-fix-ipv6-connectivity/, but you can also check on Mac or Linux with:
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 10.47.118.108 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 fe80:2881:c99f:19d5:72ed%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): {223.151.69.25, 58.229.210.39}
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 20:5c:7b:3d:03:be
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 30:b6:be:7f:f4:f9
}
Resolving Connectivity Issues in Wired and Wireless Networks
When it comes to transmitting data, you may choose to use either a wired or wireless (Wi-Fi) medium at the physical and data layer to send the data to your router.
Troubleshooting on Apple macOS / OSX Versions
No matter which version of OSX or macOS you are running - whether it’s 10.14.4, 11.4.6, or 12.0.7 - there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a series of correlated values over time, which is where automated remote troubleshooting becomes particularly useful, especially for teams that work remotely and practice Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
One useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of the 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 generate a wide range of logs, although much of it is only useful for wireless troubleshooting, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & will execute the tool in the background, writing logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively (despite minimal interaction), you can use sudo /usr/bin/sysdiagnose, which will prompt 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 Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB.
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