How Can I Check Common Wifi No Access

Explanation of Internet Protocol Address Assignment

When using the Internet, you may be assigned a Public IPv4 address such as 120.84.27.162 or an IPv6 address like 2000:cd93:2f97:5739:5c82:a365:32c4:1724. It is possible to verify this by visiting https://test-ipv6.com/. However, explaining and discussing these addresses, as well as MAC addresses such as 66:33:36:81:67:6f, can be prone to errors and become complex, particularly for individuals who are not technologically savvy. Additionally, this method does not provide any historical data, particularly regarding past issues.

Procedure for Accessing Websites

In order to access a website such as https://stracke.co, the initial step involves accessing a DNS server to translate the combined host portion (stracke) and Top Level Domain (co) of the URL into an IP address, such as 155.231.185.29. When making web requests, your computer and browser actually include its type, for example:
Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16

Significance of Default Gateways

Typically, your default gateway is an automatically configured address via DHCP. You will receive a default gateway, such as 172.30.159.161 (although they generally end in .1 or .254 based on the scope size). This is where your computer sends all its traffic to be routed onwards. For a detailed explanation of IPv6, you can refer to our guide on how-to-fix-ipv6-connectivity/. Alternatively, you can perform a 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  172.30.159.161    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:bbdf:87bb:c30b:2e12%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): {192.211.160.213, 241.67.71.115}
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 66:33:36:81:67:6f
  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 dc:17:98:bc:a4:ca
}

Methods for Resolving Issues with Wired or Wireless Connections

When transmitting data to your router, it is common to use either a wired or wireless (Wi-Fi) medium at the physical and data layer.

Solutions for Apple macOS / OSX Users

Irrespective of the version of OSX/macOS you are using, whether it’s 10.15.4, 11.2.3, or 12.2.9, there exists a variety of troubleshooting tools. However, these tools, along with manual interventions and scripts, do not provide a series of interconnected values over time. This is where automated remote troubleshooting comes in handy, particularly for teams that have adopted remote work and Work From Anywhere (WFA) practices.

Pre-installed Scripts That Offer Assistance

One particularly 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 logs for troubleshooting purposes. Furthermore, the sysdiagnose tool can be utilized to generate a multitude of logs (although many of them are related to wireless and are point-in-time, similar to wdutil).

Running sudo nohup /usr/bin/sysdiagnose -u & will execute it in the background and write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively (even though there isn’t much interaction), you can use
sudo /usr/bin/sysdiagnose, which will display a privacy warning. When not run in the background, it should open Finder in the appropriate location, or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to direct Finder to the path. It’s important to be cautious of the file sizes, which are approximately 300MB.

Possibly Helpful Videos

Video	Title	Channel
	WLAN Troubleshooting David Coleman WLPC US Phoenix 2016	Wireless LAN Professionals
	TIP OpenWifi Demo Network Setup for WLPC Drew Lentz WLPC Prague 2022	Wireless LAN Professionals
	Apples to Apples: An Analysis of the Effects of mDNS Traffic Bryan Ward WLPC Phoenix 2023	Wireless LAN Professionals
	The Importance of Broadcast/Multicast Filtering in Wi-Fi HD Arjan Koopen WLPC EU Budapest 2016	Wireless LAN Professionals
	IEEE 802 11kvr Perry Correll WLPC Phoenix 2019	Wireless LAN Professionals

Table 1.0 - Video Help