Fix Wifi No Access

Understanding Internet Addressing

When connecting to the Internet, you are assigned a Public IPv4 address, such as 241.43.4.69, or an IPv6 address, such as 2000:711f:ea52:e0f4:a68:521e:f479:45ad. You can verify your address by visiting https://test-ipv6.com/. However, communicating these addresses, or MAC addresses like 22:12:e6:0f:f9:a2, can be complex and error-prone, especially for those unfamiliar with technical jargon. Furthermore, this method does not provide any historical data, particularly during previous issues.

Navigating the World Wide Web

Accessing a webpage such as https://morar.biz involves initially contacting a DNS server to translate the host portion (morar) and the Top Level Domain (biz) of the URL into an IP address, like 201.26.177.119. Your computer and browser include important information with each web request, for example: Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)

Significance of Default Gateways

The default gateway is typically an automatically configured address obtained via DHCP, such as 172.31.164.180 (usually ending in .1 or .254 depending on the scope size). This gateway is where your computer sends all its traffic to be routed onwards. For detailed guidance on IPv6 connectivity, read our in-depth article on how-to-fix-ipv6-connectivity/. To check on Mac or Linux, use 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  172.31.164.180    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:a29a:9852:9870:a91f%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): {110.229.6.181, 221.193.23.117}
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 22:12:e6:0f:f9:a2
  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 99:8e:5a:69:86:ae
}

Resolving Issues with Wired and Wireless Connections

When it comes to transmitting 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

Regardless of which version of OSX/macOS you are running - whether it’s 10.12.8, 11.0.5, or 12.0.7 - there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes essential, particularly for teams that are embracing remote work and Work From Anywhere (WFA) setups.

Useful Built-in Scripts

One invaluable tool 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. Furthermore, the “sysdiagnose” tool can be used to generate a wide variety of logs, although much of it is only relevant to a specific point in time in relation to wireless, similar to wdutil.

Running “sudo nohup /usr/bin/sysdiagnose -u &” will execute the tool in the background and write logs to “/var/tmp/.tar.gz.” If you prefer to run it interactively, you can use “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” or use Finder with Cmd+Shift+G to locate the path. However, be cautious of the file sizes, as they can be around 300MB or more.

Possibly Helpful Videos

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	Bad Wi-Fi? Are you SURE it's a wireless problem? Here's how to find out	Wireless LAN Professionals
	Solving Wi-Fi problems in record time John Anderson WLPC US Phoenix 2017	Wireless LAN Professionals
	WiFiShark Fu Eddie Forero WLPC Phoenix 2019	Wireless LAN Professionals
	Wireless Packet Captures with Multiple Adapters Yer Yang WLPC Phoenix 2019	Wireless LAN Professionals
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Table 1.0 - Video Help