How Do You Support Wifi Router Issues

The Functioning of Internet Addressing

When using the Internet, individuals could be assigned a Public IPv4 address, such as 226.65.151.216, or an IPv6 address, such as 2000:451d:d09f:acae:2bfe:84f8:dc6a:ffe0. Verification of this can be done at https://test-ipv6.com/. However, relaying these addresses or MAC addresses, such as 8d:97:13:af:d1:3a, to those not familiar with technology can lead to errors and complications. Furthermore, there is a lack of historical data.

Navigating the Internet

When attempting to access a webpage, such as https://gibson-morar.net, one must initially contact a DNS server in order to convert the host portion (gibson-morar) along with the Top Level Domain (net) of the URL to an IP address, such as 160.172.255.140. Each web request from a 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

The Significance of Default Gateways

The default gateway is generally an address configured automatically through DHCP. An example being 172.17.183.225 (typically ending in .1 or .254 based on the scope size), this is where a computer sends all traffic to be routed onwards. For IPv6, more information can be found at how-to-fix-ipv6-connectivity/, but verification can be done 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  172.17.183.225    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   fe80:5f92:7035:a452:933d%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): {88.43.49.156, 166.168.58.10}
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 8d:97:13:af:d1:3a
  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 19:57:ba:67:7b:92
}

Resolving Connectivity Issues for Wired and Wireless Networks

Whether you are utilizing a wired or wireless (Wi-Fi) medium to transmit data to your router, connectivity issues at the physical and data layer can be frustrating.

Troubleshooting Tips for Apple macOS / OSX

No matter which version of OSX/macOS you are operating on, be it 10.14.9, 11.2.5, or 12.1.5, there is a variety of tools available for troubleshooting. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes invaluable, especially for teams that are engaged in remote work and Work From Anywhere (WFA) setups.

Useful Built-in Scripts

One of the most useful tools on OSX/macOS is the sudo wdutil info command, which provides a dump to the CLI of current wireless related settings 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 related to wireless settings and is not time-based, similar to wdutil.

To run it in the background, use sudo nohup /usr/bin/sysdiagnose -u & and it will write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively (although there is minimal interaction), use sudo /usr/bin/sysdiagnose and it will trigger a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to locate the path. However, be cautious of the file sizes, as they are typically around 300MB.

Possibly Helpful Videos

Video	Title	Channel
	WiFiShark Fu Eddie Forero WLPC Phoenix 2019	Wireless LAN Professionals
	What Problem is UWB Trying to Solve with Stephen Cooper	Wireless LAN Professionals
	Wireless Association & Authentication Pass-Fail Brian Long WLPC US Phoenix 2017	Wireless LAN Professionals
	Securing the World's Most Dangerous Wi-Fi Network Colin Vallance WLPC Phoenix 2020	Wireless LAN Professionals
	Next Generation Troubleshooting with Meraki Wireless Devin Barger WLPC Prague 2018	Wireless LAN Professionals

Table 1.0 - Video Help