Why coin wallet shows only 1 connection? I have wallet software (compile for my altcoin) and there are 3 nodes running. When i run wallet software in Mac (not core wallet), it shows only one connection to altcoin network, when it should be 3. The 3 IPs are added through dns seeds. 

Why wallet software is not doing dns lookup and not connecting to 3 nodes?

There is only one IP hardcoded into chainparamsbase.cpp. I cannot hardcode more IP into the code, wallets already compiled, which is why i am adding node IPs into DNS seeder.

Am i doing something wrong?
As you said you have only 1 IP hardcoded in chainparams.cpp and when you run your wallet without any .conf file with added nodes it will lookup only for the IP given in the source code.

If you want to add more nodes just write:

addnode=ip.ip.ip.ip


in your coin.conf file. Restart your wallet and it will try to sync to new nodes also.

If you need to hardcode the IPs in your wallet you can contact me here: https://bitcointalk.org/index.php?topic=3196213.0