How To Understand Wifi Issues
Understanding the Function of Internet Addressing
When connecting to the Internet, it’s common to have a Public IPv4 address, such as 50.160.31.247, or an IPv6 address, like 2000:de35:ef11:d589:9f92:3f9:4bba:3800. This information can be verified using a website like https://test-ipv6.com/. However, conveying these addresses or MAC addresses such as 76:1b:60:54:d6:3b to those who aren’t technically inclined tends to be error-prone and complex. Moreover, this method lacks the ability to provide historical data, especially when past issues have occurred.
How to Reach Websites on the Internet
In order to access a website, like https://dooley.info, you first need to connect to a DNS server to convert the combination of the host portion (dooley) and the Top Level Domain (info) of the URL into an IP address, for example 14.88.235.131. When making web requests, your computer and browser automatically send their type, such as Mozilla/5.0 (compatible; MSIE 9.0; AOL 9.7; AOLBuild 4343.19; Windows NT 6.1; WOW64; Trident/5.0; FunWebProducts)
The Significance of Default Gateways
A default gateway is usually an address that is automatically assigned through DHCP. The default gateway, such as 192.168.75.176 (usually ending in .1 or .254 depending on the scope size), is where your computer sends all its traffic to be routed further. For IPv6, you can find more detailed information on how-to-fix-ipv6-connectivity/. Additionally, it is possible to 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 192.168.75.176 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:d2b8:b249:a9dd:dee0%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): {145.93.203.242, 77.254.146.181}
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 76:1b:60:54:d6:3b
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 e4:9c:93:81:43:55
}
Resolving Issues with Wired and Wireless Connections
When it comes to sending data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX
Regardless of the version of OSX/macOS you’re using, whether it’s 10.12.2, 11.1.8, or 12.1.9, there are various troubleshooting tools available. However, these manual actions and scripts don’t provide a set of correlated values over time. This is where automated remote troubleshooting becomes essential, especially for teams that embrace remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
A highly valuable tool on OSX/macOS is 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. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although much of it is point-in-time only in relation 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 an interactive experience, you can run sudo /usr/bin/sysdiagnose, which will give a privacy warning. When not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp and be cautious of the file sizes, which are around 300MB.
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 🏠🏝🛰.
