ISP Delivery: DCSpeedTest.com via ETHERNET
Measures Download + Upload Mbps. Must use Ethernet — WiFi pollutes this layer with Layer 4 noise.
Latency: Ping ms from DCSpeedTest.com
Run speed.cloudflare.com for packet loss
Even 0.1% packet loss = audible audio glitches on calls and music
Run DCSpeedTest: Ethernet result vs WiFi result
Fix: 5 GHz band, move router, or Ethernet cable to the room
Compare devices on same WiFi. One device much slower = that device has old WiFi adapter, active VPN, or outdated drivers.