Troubleshoot Wifi Internet Issues
Understanding Internet Protocol Addressing
When using the Internet, you are assigned a Public IPv4 address such as 97.134.69.254 or an IPv6 address like 2000:534d:ed4e:643f:7e22:ed30:5231:4d1e. This information can be verified at https://test-ipv6.com/. However, conveying these addresses to non-technical individuals or referencing MAC addresses like ca:b8:c8:ea:33:aa can lead to errors and complexity, with no inclusion of historical data.
Navigating Websites
When accessing a website such as https://hand.io, the first step is to contact a DNS server to convert the host portion (hand) combined with the Top Level Domain (io) of the URL to an IP address like 224.196.25.202. Furthermore, all web requests from your computer and browser include your 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)
Significance of Default Gateways
The default gateway, typically obtained through DHCP, is an automatically configured address like 192.0.0.5 (often ending in .1 or .254 based on scope size). This is where your computer forwards all its traffic for routing onward. For IPv6, a comprehensive guide can be found at how-to-fix-ipv6-connectivity/, and verification 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 192.0.0.5 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 fe80:15c3:981c:cb5c:2d28%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): {59.89.100.119, 15.234.155.252}
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 ca:b8:c8:ea:33:aa
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 50:bb:46:b1:56:a3
}
Resolve Issues with Wired and Wireless Connectivity
When sending data to your router, it’s important to troubleshoot any issues that may arise at the physical and data layer, whether using a wired or wireless (Wi-Fi) medium.
Tips for Troubleshooting on Apple macOS / OSX
Regardless of the version of OSX/macOS you are using, whether it’s 10.13.4, 11.6.5, or 12.3.4, there are a variety of troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time. This is where automated remote troubleshooting becomes particularly useful, especially for teams that are embracing remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
A helpful tool on OSX/macOS is the sudo wdutil info, which provides a dump of current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although most are point-in-time only in relation to wireless, similar to wdutil.
To run sudo nohup /usr/bin/sysdiagnose -u & in the background and write logs to /var/tmp/<blah>.tar.gz. For an interactive experience (although there is not much interaction), you can run sudo /usr/bin/sysdiagnose and it will display a privacy warning. If not run in the background, it should open Finder in the correct location or you can navigate to /var/tmp or use Finder with Cmd+Shift+G to point Finder to the path. However, be aware of the file sizes, which are approximately 300MB.
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