Test Common Wifi Issues
Understanding Internet Addressing
When connected to the Internet, you are assigned either a Public IPv4 address (e.g. 147.25.104.79) or an IPv6 address (e.g. 2000:eab1:6b66:4855:3a59:d223:2005:658). You can verify this information by visiting https://test-ipv6.com/. However, relaying these addresses to non-technical individuals or even mentioning MAC addresses like b8:96:45:cc:2a:f4 can be prone to errors and quickly become complex. Moreover, this method does not provide any historical data, particularly during previous issues.
Navigating the Web
Accessing a webpage, such as https://friesen.biz, involves initially contacting a DNS server to convert the host portion (friesen) and the Top Level Domain (biz) of the URL into an IP address, such as 93.31.252.136. Additionally, your computer and browser transmit its type with all web requests, for example: Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)
Recognizing the Significance of Default Gateways
The default gateway is typically an address configured automatically through DHCP, such as 172.26.40.253 (although they often end in .1 or .254 depending on the scope size). This is where your computer directs all its traffic to be routed onwards. For IPv6, you can delve into the topic further in how-to-fix-ipv6-connectivity/; however, you can verify this on Mac or Linux by 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 172.26.40.253 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 fe80:15a7:90c6:a42e:74a2%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): {25.1.201.48, 225.26.184.209}
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 b8:96:45:cc:2a:f4
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 5d:f4:3e:51:c5:d4
}
Resolve Issues with Wired or Wireless Connections
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.
Tips for Apple macOS / OSX Users
No matter which version of OSX/macOS you are currently using, whether it’s 10.14.5, 11.6.1, or 12.3.6, there are various tools available for troubleshooting. However, these manual actions and scripts fail to provide a series of correlated values over time. For teams that embrace remote work and Work From Anywhere (WFA), automated remote troubleshooting can be extremely helpful in this regard.
Useful Built-in Scripts
One extremely helpful tool on OSX/macOS is the sudo wdutil info, which provides a dump of current wireless related settings to the command line interface, and can also be configured to generate specific logs for troubleshooting purposes. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is only relevant to wireless settings at a specific point in time, just like wdutil.
To run sudo nohup /usr/bin/sysdiagnose -u & in the background and write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can execute sudo /usr/bin/sysdiagnose and it will provide a privacy warning. Running it in the background should open Finder in the correct location or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to point to the path, but be cautious of the file sizes, which may be around 300MB or more.
Possibly Helpful Videos
P.S. Tips For Remote Network and Client Support
Digital work requires reliable connectivity. Whether for low latency or regular data streams, Wi-Fi, DNS, and network issues cause teams to lose time and productivity. Even worse is when support teams waste time trying to recreate and isolate issues! See how PanSift saves time, money, and frustration on all sides with instant remote troubleshooting 🏠🏝🛰.
