How Can I Fix Common Wifi No Access
Functioning of Internet Addressing
Internet addresses come in two main forms: Public IPv4 like 188.140.39.70 and IPv6 like 2000:387b:4ae8:981c:562d:3b5:32c6:fc12. You can verify your internet address at https://test-ipv6.com/. However, conveying these addresses to non-technical individuals or referencing MAC addresses such as 32:b9:5f:f2:ef:b7 can be prone to errors and quickly become complex. Moreover, this method does not provide any historical data, especially from past incidents.
Web Page Access
When attempting to reach a web page such as https://robel.biz, the initial step involves accessing a DNS server to translate the host (robel) combined with the Top Level Domain (biz) of the URL into an IP address such as 40.71.198.157. Your computer and browser specifies its type with every web request, for example: Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
Significance of Default Gateways
The default gateway is usually an automatically configured address via DHCP. It typically ends in .1 or .254 depending on the scope size and serves as the destination for all outgoing traffic from your computer. For insights into IPv6, refer to our in-depth guide on how-to-fix-ipv6-connectivity/. On Mac or Linux, you can check this with:
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 172.24.60.172 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 fe80:2c39:4688:d56e:2e8d%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): {77.147.56.74, 22.122.151.62}
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 32:b9:5f:f2:ef:b7
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 30:41:33:98:c6:b3
}
Resolving Issues with Wired and Wireless Connections
When you are transmitting data to your router, you might be using either a wired or a wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX
Regardless of the version of OSX/macOS you are using, whether it’s 10.11.2, 11.4.6, or 12.0.4, there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes essential, especially for teams that support remote work and Work From Anywhere (WFA).
Utilizing Built-in Scripts for Assistance
A highly useful 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. Moreover, the sysdiagnose tool can be used to generate a comprehensive range of logs, although much of it is only relevant to wireless settings, similar to wdutil.
To run it in the background and generate logs in /var/tmp/<blah>.tar.gz, you can use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, you can use sudo /usr/bin/sysdiagnose, which will display 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. Keep in mind that the file sizes are approximately 300MB.
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