How Can I Fix Wifi Issues

Understanding How Internet Addressing Functions When using the Internet, it’s common to have either a Public IPv4 address, such as 132.125.168.122, or an IPv6 address, like 2000:bbde:b28a:cf:1f65:4ae7:c41a:c1aa. This can be verified at https://test-ipv6.com/. However, explaining these addresses to non-technical individuals, or even mentioning MAC addresses, such as 21:b6:a6:db:7c:ab, can become quite complex and prone to errors. Understanding How Internet Addressing Functions When using the Internet, it’s common to have either a Public IPv4 address, such as 132.125.168.122, or an IPv6 address, like 2000:bbde:b28a:cf:1f65:4ae7:c41a:c1aa. This can be verified at https://test-ipv6.com/. However, explaining these addresses to non-technical individuals, or even mentioning MAC addresses, such as 21:b6:a6:db:7c:ab, can become quite complex and prone to errors.

Understanding How Internet Addressing Functions

When using the Internet, it’s common to have either a Public IPv4 address, such as 132.125.168.122, or an IPv6 address, like 2000:bbde:b28a:cf:1f65:4ae7:c41a:c1aa. This can be verified at https://test-ipv6.com/. However, explaining these addresses to non-technical individuals, or even mentioning MAC addresses, such as 21:b6:a6:db:7c:ab, can become quite complex and prone to errors. Furthermore, this method lacks historical data, especially in the case of past issues.

When attempting to access a website, such as https://davis.org, the initial step involves contacting a DNS server to convert the host part (davis) along with the Top Level Domain (org) of the URL into an IP address, such as 58.29.228.226. Each web request from your computer and browser includes its type, 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

The default gateway is typically an address that’s automatically configured via DHCP. You’ll be assigned a default gateway, such as 192.168.155.69 (although they usually end in .1 or .254, depending on the scope size), and this is where your computer sends all its traffic to be routed onwards. For IPv6, we have an in-depth guide on how-to-fix-ipv6-connectivity/, but 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  192.168.155.69    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   fe80:50d7:bc8a:b757:5d9b%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): {117.234.149.186, 139.43.247.86}
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 21:b6:a6:db:7c:ab
  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 5d:3e:78:ae:e4:f2
}

Solutions for Wired and Wireless Connectivity Issues

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

Troubleshooting Tips for Apple macOS / OSX

No matter which version of OSX/macOS you’re using, whether it’s 10.11.4, 11.6.9, or 12.1.6, there are various troubleshooting tools available. However, manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes valuable, especially for teams embracing remote work and Work From Anywhere (WFA).

Useful Built-in Scripts

On OSX/macOS, the sudo wdutil info tool provides a CLI dump of current wireless settings and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a variety of logs, although many of them are only point-in-time related to wireless, similar to wdutil.

To run it in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. For an interactive run, use sudo /usr/bin/sysdiagnose which will provide a privacy warning. The file sizes are approximately 300MB, so be cautious of that.

Possibly Helpful Videos

Video Title Channel
Wireless Association & Authentication Pass-Fail Brian Long WLPC US Phoenix 2017 Wireless LAN Professionals
The Importance of Broadcast/Multicast Filtering in Wi-Fi HD Arjan Koopen WLPC EU Budapest 2016 Wireless LAN Professionals
Wi Fi Issues in the Wild Gopinath K.N. WLPC Phoenix 2018 Wireless LAN Professionals
Automated Root Cause Analysis in Wireless Networks Karan Gupta Wireless LAN Professionals
178 Why Wyebot with Roger Sands Wireless LAN Professionals
Table 1.0 - Video Help



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