Why can the bars on my phone look fine while the router still performs poorly?

Phone bars are a rough indicator, not a proper network assessment. Routers and phones may support different bands, antenna arrangements and carrier features, and good-looking signal strength does not guarantee good quality, low interference or adequate upload performance. That is why more meaningful figures such as RSRP, RSRQ and SINR are often used when testing router performance.

Comset normally treats a phone as a clue, not as the final authority. A site can look healthy on a handset and still need better antenna design or a different carrier once the actual router is installed.