How Can I Understand Common Wifi Issues

How the System of Internet Addressing Functions

When using the Internet, you might receive a Public IPv4 address, such as 203.165.254.68, or an IPv6 address, like 2000:40d3:9e86:a347:4063:36a3:e1c1:b5b6. This information can be verified at https://test-ipv6.com/. However, for those not familiar with technical aspects, conveying and managing these addresses, as well as calling out MAC addresses like 36:fb:2c:4c:ca:0c, can quickly become error-prone and complicated. Moreover, this does not provide any historical data, particularly related to past issues.

Navigating the Internet

When attempting to access a webpage, such as https://walter.co, the first step is to reach out to a DNS server to convert the host portion (walter) combined with the Top Level Domain (co) of the URL into an IP address, such as 32.54.117.183. Whenever a web request is made, your computer and browser also communicate their type, for example: <br>Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16

The Significance of Standard Gateways

Typically, your default gateway is an address that is automatically configured via DHCP. This gateway is assigned an IP address such as 172.30.96.251 (often ending in .1 or .254 based on the scope size), and it serves as the point to which your computer sends all its traffic for further routing. For insights on IPv6, an in-depth guide is available at how-to-fix-ipv6-connectivity/. On Mac or Linux systems, you can verify this information using:

### IPv4 Routes and the Host IPv4 Route Table (inc. VPN)
```netstat -rn -f inet | egrep -i "default|0/1|128.0/1"```

<pre>
0/1      172.18.12.193  UGScg  utun3
default  172.30.96.251    UGScg  en0
128.0/1  172.18.12.193  UGSc   utun3</pre>

**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. 

<pre>
default   fe80:e595:2e9c:8b70:2766%en0  UGcg   en0
default   fe80::%utun0                   UGcIg  utun0
default   fe80::%utun1                   UGcIg  utun1
default   fe80::%utun2                   UGcIg  utun2
2000::/3  utun3                          USc    utun3</pre>

**Note:** We are not just looking for the default but also for any VPN that overrides the public v6 address space.
<br>

## Debugging DHCP for both IPv4 and IPv6

To get a look at the low level DHCP configuration (Mac/Linux): 

```ipconfig getpacket en0```

<pre>
...
domain_name_server (ip_mult): {20.29.177.44, 146.30.253.147}
end (none):
...</pre>

So, in the above we are not getting IPv6 DNS servers from the DHCPv4 reply but...

```ipconfig getv6packet en0```

<pre>
DHCPv6 REPLY (7) Transaction ID 0x80940b Length 76
Options[4] = {
  CLIENTID (1) Length 14: DUID LLT HW 1 Time 668691856 Addr 36:fb:2c:4c:ca:0c
  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 5b:5a:c9:3c:6f:4e
}</pre>




## Resolving Connectivity Issues in Wired and Wireless Networks

When it comes to transmitting data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
### Troubleshooting Tips for Apple macOS / OSX Users
Regardless of whether you are running OSX/macOS version ```10.14.9```, ```11.2.8```, or ```12.0.6```, there are various troubleshooting tools available. However, manual actions and scripts do not provide a series of correlated values over time. For this reason, automated remote troubleshooting is particularly beneficial for teams that have adopted remote work and Work From Anywhere (WFA) practices.
#### Useful Built-in Scripts
One valuable tool for OSX/macOS users is the ```sudo wdutil info``` command, which provides a dump of current wireless settings to the command line interface (CLI), and can be configured to generate specific troubleshooting logs. Additionally, the ```sysdiagnose``` tool offers a more comprehensive approach by generating numerous logs (although many are point-in-time only, similar to wdutil).

To run ```sysdiagnose``` in the background and generate logs in ```/var/tmp/<blah>.tar.gz```, use the command ```sudo nohup /usr/bin/sysdiagnose -u &```. If you prefer to run it interactively, use ```sudo /usr/bin/sysdiagnose``` but be mindful of the large file sizes of about 300MB.
## Possibly Helpful Videos

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|Video | Title | Channel |
| :---: | :---: | :---: |
|<a href="https://www.youtube.com/watch?v=XIgyJ0f8Zl4" data-lity><img src="https://i.ytimg.com/vi/XIgyJ0f8Zl4/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=XIgyJ0f8Zl4" data-lity>Wi Fi Issues in the Wild   Gopinath K.N.   WLPC Phoenix 2018</a>|<a target="_blank" href="https://www.youtube.com/channel/UCIzBSS46vcqhwmBZ7ZpY-yg" >Wireless LAN Professionals</a>|
|<a href="https://www.youtube.com/watch?v=PVa0C60HgyM" data-lity><img src="https://i.ytimg.com/vi/PVa0C60HgyM/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=PVa0C60HgyM" data-lity>Wireless Adjuster Certification - Do You Need It?</a>|<a target="_blank" href="https://www.youtube.com/channel/UCIzBSS46vcqhwmBZ7ZpY-yg" >Wireless LAN Professionals</a>|
|<a href="https://www.youtube.com/watch?v=r9oXNxgAKhM" data-lity><img src="https://i.ytimg.com/vi/r9oXNxgAKhM/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=r9oXNxgAKhM" data-lity>Benefits of WPA3, Enhanced Open, and Easy Connect   P. Ebbecke, P. Correll   WLPC Prague 2018</a>|<a target="_blank" href="https://www.youtube.com/channel/UCIzBSS46vcqhwmBZ7ZpY-yg" >Wireless LAN Professionals</a>|
|<a href="https://www.youtube.com/watch?v=EWURmcra5_4" data-lity><img src="https://i.ytimg.com/vi/EWURmcra5_4/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=EWURmcra5_4" data-lity>Wireless Association &amp; Authentication Pass-Fail   Brian Long   WLPC US Phoenix 2017</a>|<a target="_blank" href="https://www.youtube.com/channel/UCIzBSS46vcqhwmBZ7ZpY-yg" >Wireless LAN Professionals</a>|
|<a href="https://www.youtube.com/watch?v=1G4qihqHZJ0" data-lity><img src="https://i.ytimg.com/vi/1G4qihqHZJ0/default.jpg" class="img-fluid"></a>|<a href="https://www.youtube.com/watch?v=1G4qihqHZJ0" data-lity>Bad Wi-Fi? Are you SURE it&#39;s a wireless problem? Here&#39;s how to find out</a>|<a target="_blank" href="https://www.youtube.com/channel/UCIzBSS46vcqhwmBZ7ZpY-yg" >Wireless LAN Professionals</a>|

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