How Can I Check Common Wifi Router Issues
Understanding Internet Addressing
When you connect to the Internet, you are assigned a Public IPv4 or IPv6 address. These addresses, such as 212.170.229.73 and 2000:3b9d:cfee:f44d:a805:5eba:fbde:e519, can be verified at https://test-ipv6.com/. Communicating or referencing these addresses, as well as MAC addresses like df:4f:ea:3f:ee:82, can be error-prone and complex, especially for those who are not well-versed in technology. Moreover, they do not provide any historical data.
Accessing Websites
Accessing a website like https://jerde.com involves utilizing a DNS server to translate the URL’s host portion and Top Level Domain into an IP address, such as 72.102.231.69. Whenever your computer and browser request a web page, they also transmit their type, such as Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko.
Understanding Default Gateways
Your default gateway is usually assigned automatically through DHCP and typically appears as an address like 192.168.212.54, often ending in .1 or .254 based on the scope size. This is where your computer directs all of its traffic to be routed onwards. For IPv6, detailed instructions on how to check this on Mac or Linux can be found at how-to-fix-ipv6-connectivity/.
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 192.168.212.54 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 fe80:6017:6d03:b47d:d9b4%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): {60.46.197.226, 204.235.11.253}
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 df:4f:ea:3f:ee:82
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 ef:05:68:5f:3b:04
}
Addressing Connectivity Issues in a Wired or Wireless Network
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 Strategies for Apple macOS / OSX Systems
Regardless of the version of OSX/macOS you are operating on, whether it’s 10.14.1, 11.1.2, 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 invaluable, especially for teams that are accustomed to remote work and Work From Anywhere (WFA).
Leveraging Pre-Installed Scripts for Assistance
One of the most useful tools on OSX/macOS is the sudo wdutil info, which provides a dump of current wireless settings to the CLI and can also be configured to generate specific logs for troubleshooting purposes. Moreover, the sysdiagnose tool offers a more comprehensive approach to generating a wide range of logs, although many logs are only related to wireless settings, much like wdutil.
To run sudo nohup /usr/bin/sysdiagnose -u & in the background, allowing it to write logs to /var/tmp/<blah>.tar.gz. For an interactive run (though there isn’t much interaction involved), execute sudo /usr/bin/sysdiagnose, which will prompt a privacy warning. If 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. Keep in mind that the file sizes are approximately 300MB.
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