It’s OK to use a low-channel (below 36) once in a while but you shouldn’t have to rely on it every day.

Newer wi-fi routers support multiple channels simultaneously, so your device could connect with one channel or another depending on signal strength. The channel is determined by the wi-fi router so you may need help changing it. These channels are prone to interference from other nearby wi-fi systems, microwave ovens and others. Don’t use a neighbor’s or a public or Xfinity wi-fi channel – they may not be secure or provide access to printers, computers, iPhones & other devices on your own network.

Be sure your own network is checked here. To check your wi-fi signal, hold the option key as you click the wi-fi menu in the upper-right corner. You’ll see information that can help diagnose any issues.