Check Wifi Connectivity
Understanding Internet Addressing
When using the Internet, you can be assigned a Public IPv4 address, such as 125.21.16.178, or an IPv6 address, like 2000:bbaa:d7bb:e05a:64ef:6871:bd0a:d542. To check your assigned address, you can visit https://test-ipv6.com/. However, conveying these addresses, or even MAC addresses like d0:05:61:cb:0b:56, can be error-prone and complex for those not well-versed in technology. Furthermore, this does not provide any historical data, particularly from past issues.
Navigating the World Wide Web
When accessing a web page, such as https://hintz.biz, the first step is to contact a DNS server to convert the host portion (hintz) along with the Top Level Domain (biz) of the URL into an IP address, like 211.129.183.131. In all web requests, your computer and browser actually include its type, for example, Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
The Significance of Default Gateways
Typically, your default gateway is an automatically configured address via DHCP. A default gateway, such as 172.27.193.228, (although they usually end in .1 or .254 depending on the scope size) is where your computer directs all its traffic for further routing. For IPv6, you can explore more on how-to-fix-ipv6-connectivity/ but it can also be checked 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 172.27.193.228 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 fe80:443f:529e:3ce5:3790%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): {134.218.26.190, 25.54.88.220}
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 d0:05:61:cb:0b:56
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 b0:b8:15:f3:01:84
}
Solutions for Wired and Wireless Connectivity
When it comes to transferring data at the physical and data layer, you have the option of using either a wired or wireless (Wi-Fi) medium to send the data to your router.
Troubleshooting Tips for Apple macOS / OSX
No matter which version of OSX/macOS you are currently using, such as 10.11.3, 11.2.6, or 12.1.7, 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 extremely useful, especially for teams that are embracing remote work and the concept of Work From Anywhere (WFA).
Useful Built-in Scripts
A very helpful tool on OSX/macOS is the sudo wdutil info, which provides a dump to the CLI of current wireless settings 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 only related to wireless issues, similar to wdutil.
Running sudo nohup /usr/bin/sysdiagnose -u & in the background will write logs to /var/tmp/<blah>.tar.gz. If you prefer to run it interactively, you can do so with sudo /usr/bin/sysdiagnose, but be aware of the large file sizes, approximately 300MB or more.
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