How To Test Common Wifi No Access

Understanding Internet Addressing When using the Internet, you are assigned a Public IPv4 address such as 242.181.212.129 or an IPv6 address like 2000:9264:b6ef:2389:31a1:a9d2:b863:dc3c. To verify your address, visit https://test-ipv6.com/. Communicating these addresses, or even mentioning MAC addresses like 0d:fa:39:d1:41:76, can be challenging and error-prone, especially for those who are not technically inclined. Understanding Internet Addressing When using the Internet, you are assigned a Public IPv4 address such as 242.181.212.129 or an IPv6 address like 2000:9264:b6ef:2389:31a1:a9d2:b863:dc3c. To verify your address, visit https://test-ipv6.com/. Communicating these addresses, or even mentioning MAC addresses like 0d:fa:39:d1:41:76, can be challenging and error-prone, especially for those who are not technically inclined.

Understanding Internet Addressing

When using the Internet, you are assigned a Public IPv4 address such as 242.181.212.129 or an IPv6 address like 2000:9264:b6ef:2389:31a1:a9d2:b863:dc3c. To verify your address, visit https://test-ipv6.com/. Communicating these addresses, or even mentioning MAC addresses like 0d:fa:39:d1:41:76, can be challenging and error-prone, especially for those who are not technically inclined. Moreover, it does not provide any historical data, particularly when dealing with past issues.

Accessing a web page, such as https://lakin.biz, involves initially contacting a DNS server to convert the host portion (lakin) and the Top Level Domain (biz) of the URL into an IP address, like 168.115.34.139. Your computer and browser sends its type with every web request, 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 automatically configured address via DHCP. This address, such as 172.19.232.234 (usually ending in .1 or .254 based on the scope size), is where your computer directs all of its traffic to be routed onwards. For IPv6, we have an in-depth discussion on how-to-fix-ipv6-connectivity/, and you can 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  172.19.232.234    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:c8f2:9caf:84a0:7d65%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): {127.168.243.253, 230.128.92.167}
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 0d:fa:39:d1:41:76
  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 8d:f3:a9:bc:90:2d
}

Fixing Connectivity Issues on Wired and Wireless Networks

When it comes to sending data to your router, you might be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.

Troubleshooting on Apple macOS / OSX

Regardless of the version of OSX/macOS you are running, whether it’s 10.13.3, 11.0.5, or 12.0.1, 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 valuable, especially for teams that embrace remote work and Work From Anywhere (WFA).

Utilizing Built-in Scripts for Assistance

One useful tool on OSX/macOS is 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. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only related to wireless settings at a specific point in time, just like wdutil.

Running sudo nohup /usr/bin/sysdiagnose -u & will execute it in the background and write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively, you can run sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp manually or use Finder with Cmd+Shift+G to navigate to the path. It’s important to note that the file sizes are approximately 300MB.

Possibly Helpful Videos

Video Title Channel
Wireless Packet Captures with Multiple Adapters Yer Yang WLPC Phoenix 2019 Wireless LAN Professionals
WIDS/WIPS / Reseller FAQ WLPC Wireless LAN Weekly EP 14 Wireless LAN Professionals
The Importance of Broadcast/Multicast Filtering in Wi-Fi HD Arjan Koopen WLPC EU Budapest 2016 Wireless LAN Professionals
TIP OpenWifi Demo Network Setup for WLPC Drew Lentz WLPC Prague 2022 Wireless LAN Professionals
Securing the World's Most Dangerous Wi-Fi Network Colin Vallance WLPC Phoenix 2020 Wireless LAN Professionals
Table 1.0 - Video Help



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