How Do You Check Wifi Router Issues
Explaining the Functionality of Internet Addressing
When using the Internet, you are assigned a unique Public IPv4 address, such as 86.196.38.38, or an IPv6 address like 2000:8d8d:43b3:8fbf:2806:ab18:aaad:8cc2. You can verify this information by visiting https://test-ipv6.com/. However, explaining and communicating these addresses, along with MAC addresses like 86:84:a1:c2:fd:b1, to individuals who are not tech-savvy can be prone to errors and quickly become complex. Furthermore, this method does not provide any historical data regarding previous issues.
Navigating the World Wide Web
Accessing a web page, such as https://larson.org, involves the initial step of contacting a DNS server to convert the host portion (larson) combined with the Top Level Domain (org) of the URL into an IP address, for example, 223.35.182.249. In every web request, your computer and browser transmit their type, indicated as Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts).
Understanding the Significance of Default Gateways
Typically, your default gateway is an automatically configured address provided through DHCP. An example of a default gateway is 172.19.90.179 (usually ending in .1 or .254, depending on the scope size), which is responsible for routing all traffic from your computer. For IPv6, you can explore more detailed information on how-to-fix-ipv6-connectivity/, and on Mac or Linux systems, you can verify it 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 172.19.90.179 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 fe80:4d80:c87a:5922:2d51%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): {206.213.188.71, 254.96.146.164}
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 86:84:a1:c2:fd:b1
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 f7:2e:36:5a:c5:53
}
Troubleshooting and Resolving Issues with Wired and Wireless Connections
When 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 Users
No matter which version of OSX/macOS you are using - whether it’s 10.11.2, 11.3.8, or 12.2.5 - 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 valuable, especially for teams that adopt remote work and Work From Anywhere (WFA) practices.
Utilizing Built-in Scripts for Assistance
A useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump to the CLI of current wireless related settings. This command can also be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool can be utilized to generate a wide range of logs, although much of the information is only relevant to the wireless connection, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will generate logs in /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (even though there isn’t much interaction involved), you can use the commandsudo /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 using Finder with Cmd+Shift+G. Keep in mind that the file sizes are approximately 300MB.
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