How Can I Check Wifi Router Issues

Explanation of IP Addressing

When you use the Internet, you are provided with a Public IPv4 address, for example, 14.134.218.240, or an IPv6 address, such as 2000:19a6:524c:4b8a:b814:5ed3:3a7a:932a. To verify this information, you can visit https://test-ipv6.com/. However, for those who are not well-versed in technology, conveying and working with such addresses, as well as MAC addresses, like 3d:9c:0c:f0:8f:e4, can be prone to errors and quickly becomes complex. Furthermore, this method does not provide any historical data, especially for past issues.

Website Accessing Process

In order to access a website such as https://wiza-morar.net, you first communicate with a DNS server to convert the host part (wiza-morar) combined with the Top Level Domain (net) of the URL into an IP address, for example, 104.241.139.189. Your computer and browser include its type with every web request, such as:
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

Your default gateway is typically an address configured automatically through DHCP, such as 192.168.101.154 (although they usually end in .1 or .254 depending on the scope size), and this is where your computer directs all its traffic for further routing. For IPv6, more information can be found at how-to-fix-ipv6-connectivity/, but you can also check 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  192.168.101.154    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   fe80:52d2:26fd:9316:c68b%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): {186.140.164.154, 81.129.243.197}
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 3d:9c:0c:f0:8f:e4
  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 51:b9:4e:34:1b:84
}

Diagnosing and Resolving Connection Issues - Wired and Wireless

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

Trouble-shooting Tips for Apple macOS / OSX

Regardless of the version of OSX/macOS you are using, whether it’s 10.15.9, 11.2.5, or 12.0.6, there are various tools available for diagnosing and resolving issues. However, these manual actions and scripts do not provide a series of correlated values over time, which is where automated remote troubleshooting can be particularly useful, especially for teams that embrace remote work and Work From Anywhere (WFA).

Utilizing Built-in Scripts

One useful tool on OSX/macOS is the sudo wdutil info command, which provides current wireless-related settings and can be configured to generate specific logs for troubleshooting purposes. Another comprehensive tool is the sysdiagnose tool, which can generate a wide range of logs, although much of it is point-in-time data in relation to wireless, similar to wdutil.

To run sysdiagnose in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. For interactive use, run the command sudo /usr/bin/sysdiagnose, which will display a privacy warning and open Finder in the correct location or allow you to navigate to /var/tmp using Cmd+Shift+G. Be mindful of the file sizes, which can be around 300MB.

Possibly Helpful Videos

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Table 1.0 - Video Help