1. Define the scope
Is one device affected or all devices? One room or everywhere? One application or all internet traffic? Intermittently or continuously? This immediately narrows the likely layer.
2. Compare wired and wireless
If practical, compare a capable wired device with a Wi‑Fi device. Good wired performance plus poor Wi‑Fi performance points toward the radio/network layer rather than the ISP access line.
3. Check the local network path
Look at device connection state, Wi‑Fi band, signal, router status, Ethernet link speeds and whether a mesh/extender backhaul is healthy. Avoid changing many radio settings simultaneously.
4. Restart thoughtfully
A restart can clear a temporary software state, but repeated restarts are evidence rather than a permanent fix. If a gateway must be restarted constantly, record the pattern and look for firmware, line or hardware causes.
5. Escalate with evidence
When contacting the ISP, useful evidence includes dates/times, whether Ethernet was also affected, gateway status, repeated test results and whether the problem is loss of service or simply lower throughput.