I'm helping two family members troubleshoot different internet setups that randomly lose connectivity for about 10–15 seconds. The problem may happen once a day or several times daily. One computer runs Windows 11 and the other runs Linux, although the Linux computer had the same issue when it previously used Windows 11. They have already replaced Ethernet cables, bypassed a network switch, tried the motherboard Ethernet ports and USB-C Ethernet adapters, changed the modem/router ports, and contacted their ISPs several times. The ISP technicians have not found anything wrong. Is there free or inexpensive software, or a reliable testing method, that can show whether the failure is occurring on the computer, local network, router, modem, or ISP connection?
2 Answers
It would also be useful to identify the exact ISP gateway/router models and check their logs. Since both connections use ISP-provided equipment, the router or modem firmware and signal quality are still possibilities even after changing cables, ports, and adapters. A bufferbloat test can reveal latency spikes when the connection is busy, although if nobody is using the connection during the outages, bufferbloat is less likely to be the cause. Their advertised speeds—1 Gbps and 2 Gbps—don’t rule out brief link or service interruptions.
Wireshark is free and can capture packets while the problem occurs, but it can be a bit overwhelming if you’re new to it. A simpler first test is to run several continuous pings at the same time: one to the local router, one to a public IP such as 1.1.1.1, and one to a hostname such as example.com. If the router ping fails, the problem is inside the home network or with the router. If the router responds but the public IP fails, the modem or ISP connection is likely involved. If the IP works but the hostname fails, investigate DNS. Save the timestamps and results so the ISP can correlate them with their logs.
That makes sense. I’ll try the simultaneous ping tests first and use Wireshark if the results aren’t clear.
Right, bufferbloat usually shows up when the connection is saturated. If the dropouts happen while the network is otherwise idle, I’d focus more on continuous pings, router logs, and the modem’s signal or event logs.