How To Support Wifi Router Issues
Understanding Internet Addressing
When connecting to the Internet, you may be assigned a Public IPv4 address (e.g. 4.161.61.241) or an IPv6 address (e.g. 2000:a9a0:156d:ee8a:b59b:a12f:bc21:735a). To verify this, you can visit https://test-ipv6.com/. Communicating these addresses or MAC addresses (e.g. 6b:47:8e:a8:ed:5f) can be complex and error-prone, especially for those who are not tech-savvy. Moreover, this information does not provide any historical data.
Navigating the World Wide Web
When accessing a webpage like https://waelchi.info, your computer initially contacts a DNS server to convert the host (waelchi) and Top Level Domain (info) of the URL into an IP address, such as 79.198.237.170. Every web request sent from your computer and browser contains information about the type, for example: Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16
Understanding the Significance of Default Gateways
Your default gateway is typically assigned automatically through DHCP and usually appears as an address ending in .1 or .254, depending on the scope size, such as 10.191.204.90. This is the point where your computer directs all its traffic to be routed onward. For troubleshooting IPv6 connectivity on Mac or Linux, you can refer to our in-depth guide: 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 10.191.204.90 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:db16:77f3:3fc1:39ee%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): {208.193.184.215, 225.109.209.152}
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 6b:47:8e:a8:ed:5f
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 d2:ac:91:63:e3:00
}
Resolving Wired and Wireless Connectivity Issues
When it comes to transferring data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Steps to Take on Apple macOS / OSX
Regardless of whether you are using OSX/macOS version 10.12.6, 11.5.1, or 12.1.2, there are various troubleshooting tools available. However, these manual actions and scripts fail to provide a set of correlated values over time. This is where automated remote troubleshooting becomes essential, especially for teams that are adapting to remote work and embracing the concept of Work From Anywhere (WFA).
Utilizing Pre-Installed Scripts for Assistance
One incredibly useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings through the CLI, and can also be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it only provides point-in-time information related to wireless, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz for you. If you prefer to run it interactively (despite minimal interaction), you can run sudo /usr/bin/sysdiagnose and it will prompt a privacy warning. When not run in the background, it should open Finder in the appropriate location, or you can navigate to /var/tmp using Cmd+Shift+G in Finder. However, be mindful of the file sizes, which are typically around 300MB.
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