What kind of lightning wallet is it? LND? Core? Or its own design?
Is it also effected when onchain fees are high? (Ex: Channel reserve gets triggered & closes channel).
Follow this guide
https://bitcointalk.org/index.php?topic=5259973.0You need your seed/addresses to be bech32 format, meaning that starts with bc1, and after you create bc1 wallet, you need to deposit an amount of 0.002BTC, after that you activate the Lightning Network option and open your channel, you will get the Node ID and use it to connect to other nodes, let's say, for example, that you want to deposit to a local store node, After creating the channel, you will pay the mining fee and wait for 3 confirmations, after which you will not need any additional fees, as the transactions are fast and with zero fees.
You can open/close the channel when onChain network is not congested to reduce the mining fee.