How Can I Troubleshoot Common Wifi Internet Issues
Mechanics of Internet Addressing
The functioning of Internet addressing is such that you are assigned a Public IPv4 address, such as 233.229.148.232, or an IPv6 address, such as 2000:f904:c815:e3c7:7922:4b:e645:f9bf. You can verify this information by going to https://test-ipv6.com/. However, explaining or communicating these addresses to individuals who aren’t tech-savvy, or even referring to MAC addresses, like bb:2e:bf:ee:d1:72, can become challenging and prone to mistakes. Furthermore, this method doesn’t provide any historical data, especially when past issues arise.
Navigating the World Wide Web
In order to access a webpage like https://jacobson.net, you first connect with a DNS server to translate the host portion (jacobson) combined with the Top Level Domain (net) of the URL into an IP address, such as 63.182.106.154. Your computer and browser send their 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)
Significance of Predefined Gateways
The default gateway is typically an address that is automatically configured via DHCP. This address, such as 10.31.163.253 (although typically ending in .1 or .254 depending on the scope size), is where your computer sends all of its traffic to be routed onwards. A detailed breakdown of IPv6 can be accessed in our write-up on how-to-fix-ipv6-connectivity/; however, the verification process can be done on Mac or Linux with:
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 10.31.163.253 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 fe80:10c2:c65d:9b43:99e%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): {162.66.195.12, 82.143.150.237}
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 bb:2e:bf:ee:d1:72
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 93:58:1b:c4:81:b3
}
Fixing Issues with Wired and Wireless Connectivity
When it comes to sending data to your router, you may be using either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Methods for Apple macOS / OSX
Regardless of the version of OSX/macOS you have, whether it’s 10.11.8, 11.5.8, or 12.3.9, 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 particularly valuable, especially for teams that have adopted remote work and Work From Anywhere (WFA) policies.
Utilizing Built-in Scripts for Assistance
One valuable tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings in the CLI, and can also be configured to generate specific logs for troubleshooting. Additionally, the more comprehensive sysdiagnose tool can be used to generate a wide range of logs, although much of the information is only relevant to a specific point in time, 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 &. If you prefer to run it interactively, use the command sudo /usr/bin/sysdiagnose, but be aware of the large file size, around 300MB.
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