Airtel — unable to use 4g network

Address: Lucknow, Uttar Pradesh

I have airtel 4g sim card but it always switches to 3g network or no network. I have tried manual setting of network then to it shows same problem.in advertisement u show it as fastest growing network i think it is baddest growing network. One question how can i port my airtel number?. Calling quality is excellent but still now i need to port number just because i have seen other 4g network giving data and network speed better than your services at more cheaper rates