How Do You DiagnOSe Common Wifi Connectivity

Understanding Internet Protocol Addressing When using the Internet, you are assigned a Public IPv4 address, such as 175.148.142.162, or an IPv6 address like 2000:53de:80ed:7208:973d:3186:66c7:5ad4. These addresses can be verified at https://test-ipv6.com/. However, attempting to convey these addresses and MAC addresses like 21:6a:94:86:13:a4 to individuals without technical expertise can lead to errors and complexity, with no provision for historical data. Understanding Internet Protocol Addressing When using the Internet, you are assigned a Public IPv4 address, such as 175.148.142.162, or an IPv6 address like 2000:53de:80ed:7208:973d:3186:66c7:5ad4. These addresses can be verified at https://test-ipv6.com/. However, attempting to convey these addresses and MAC addresses like 21:6a:94:86:13:a4 to individuals without technical expertise can lead to errors and complexity, with no provision for historical data.

Understanding Internet Protocol Addressing

When using the Internet, you are assigned a Public IPv4 address, such as 175.148.142.162, or an IPv6 address like 2000:53de:80ed:7208:973d:3186:66c7:5ad4. These addresses can be verified at https://test-ipv6.com/. However, attempting to convey these addresses and MAC addresses like 21:6a:94:86:13:a4 to individuals without technical expertise can lead to errors and complexity, with no provision for historical data.

Web Navigation Process

In order to reach a specific web page, for example, https://heathcote.biz, your device initially communicates with a DNS server to translate the host portion (heathcote) and the Top Level Domain (biz) of the URL into an IP address, such as 41.142.8.11. Furthermore, the web requests transmitted by your computer and browser are accompanied by information detailing the type, such as
Mozilla/5.0 (Windows NT x.y; Win64; x64; rv:10.0) Gecko/20100101 Firefox/10.0

Significance of Default Gateways

Typically, your default gateway is automatically configured through DHCP and is represented by an address like 172.18.181.54 (commonly ending in .1 or .254 depending on scope size). This gateway serves as the point where your computer directs all its traffic for further routing. For IPv6, a detailed exploration is available at how-to-fix-ipv6-connectivity/ and can be verified 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  172.18.181.54    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:ef16:1c0:52a6:6522%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): {159.16.59.223, 15.44.189.117}
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 21:6a:94:86:13:a4
  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 45:5c:17:ed:d3:98
}

Diagnosing and Resolving Connectivity Issues

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

Tips for Troubleshooting on Apple Operating Systems

Regardless of whether you are using OSX or macOS, whether it’s version 10.11.9, 11.2.5, or 12.0.4, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes essential, particularly for teams that are engaged in remote work and Work From Anywhere (WFA).

Useful Built-in Tools

One of the most helpful tools on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to produce a wide range of logs, although much of it is only relevant to wireless issues, similar to wdutil.

By runningsudo nohup /usr/bin/sysdiagnose -u &, the tool can be run in the background and will write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can execute sudo /usr/bin/sysdiagnose, which 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 point Finder to the path. However, beware of the file sizes, which are generally around 300MB.

Possibly Helpful Videos

Video Title Channel
WLAN Troubleshooting David Coleman WLPC US Phoenix 2016 Wireless LAN Professionals
Wireless Adjuster Certification - Do You Need It? Wireless LAN Professionals
Do You Have A Wired or Wireless Problem Wireless LAN Professionals
WIDS/WIPS / Reseller FAQ WLPC Wireless LAN Weekly EP 14 Wireless LAN Professionals
Wireless Packet Captures with Multiple Adapters Yer Yang WLPC Phoenix 2019 Wireless LAN Professionals
Table 1.0 - Video Help



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