Troubleshooting Network Connection: Two Computers Subnet Can't Talk, Ping Outside World
This article focuses on providing a detailed guide on troubleshooting a specific network connection issue, particularly when two computers in a subnet can't communicate or ping the outside world. This topic is relevant to the global audience interested in improving their networking knowledge and solving common connectivity problems.
Background and Context
In many home and business environments, computers, laptops, and other devices connect to the internet via a router, which acts as a gateway between the local network (subnet) and the wider internet. Sometimes, issues arise where two computers within the same subnet are unable to communicate, or cannot reach the internet despite the network appearing functional.
Common Causes
The causes of this problem may be due to misconfigured IP settings, DNS issues, subnet conflicts, or faulty network hardware. In the scenario described, we have two laptops - a MacBook 19 (late 2019, running macOS Sonoma 14.7.1) and a Huawei MateBook 14 Laptop (running a recent version of Windows).
Verifying the Problem
The first step in troubleshooting the problem is confirming the symptoms. On the MacBook, use the following command to check the connectivity:
$ ping 8.8.8.8
On the Huawei MateBook 14, use Windows PowerShell to run:
PS> ping 8.8.8.8
If both laptops fail to get a response from Google's public DNS server (8.8.8.8), it may indicate a broader connectivity problem. If, however, one laptop can successfully ping 8.8.8.8 while the other cannot, it suggests a local network issue.
Possible Solutions
1. Check IP Address Settings
Ensure both laptops are obtaining IP addresses via DHCP (Dynamic Host Configuration Protocol) from the router. Invalid IP settings, such as improper subnet masks, can cause connectivity issues:
- On the MacBook, open System Preferences > Network > Wi-Fi > Advanced > TCP/IP > select 'Using DHCP' for the Configure IPv4 dropdown
- On the Huawei MateBook 14, open Settings > Network & Internet > Wi-Fi > Properties > IP settings > ensure 'Automatic (DHCP)' is selected
2. Check the DNS Settings
Manual or incorrect DNS settings may create issues when attempting to reach external resources. Ensure both laptops rely on their DHCP server to provide DNS details:
- On the MacBook, under System Preferences > Network > Wi-Fi > Advanced > DNS, remove any manual DNS entries; they will be automatically populated if Using DHCP is active
- On the Huawei MateBook 14, under Settings > Network & Internet > Wi-Fi > Properties > DNS, make sure no manual DNS entries exist and 'Obtain DNS server address automatically' is selected
3. Confirm Subnet Settings
Confirm that both laptops are using the expected subnet mask and that no conflicts emerge:
On the MacBook, the subnet mask value should be automatically derived from the router; this can be verified under System Preferences > Network > Wi-Fi > Advanced > TCP/IP (e.g., 255.255.255.0 for 24-bit subnet)
On the Huawei MateBook 14, the subnet mask value should also be derived automatically; this can be seen under Settings > Network & Internet > Wi-Fi > Properties (e.g., 255.255.255.0 for 24-bit subnet)
4. Test the Connectivity Between the Computers
With the laptops configured as described, a simple test can be executed:
On the MacBook, open Terminal and enter:
pingWhere
A similar process can also be executed on the Huawei MateBook 14, using PowerShell:
On the Huawei MateBook 14, open PowerShell and enter:
pingWhere
If successful, there is clear LAN-to-LAN connectivity. If the ping fails, confirm that there are no firewall rules or configuration preventing this connectivity.
References
- Article: How to Troubleshoot Your Internet Connection
- Article: Problems of Pinging Google
- Online Resource: Wireshark (network packet analysis tool to further examine network traffic)