Litecoin clone - Timeout downloading headers from peer disconnecting

I am creating an atlcoin cloned from litecoin (version 0.15). The genesis blocks are mined and I have setup two nodes on VPS that are connected to each other. I can mine new blocks and sync them with each other perfectly on the regtest network. Unfortunately I am unable to do this for either the mainnet or the testnet. I am stuck as the nodes are not syncing with each other. I have mined coins on one peer but they are not downloading in the other one. I get the following message in the debug.log file

2018-01-08 06:20:39 Timeout downloading headers from peer=2, disconnecting
2018-01-08 06:20:41 receive version message: /GlobalcoinCore:0.15.0.1/: version 70015, blocks=3, us=165.227.36.100:19335, peer=4

Any idea why they are not syncing on the regtest but not on either of the others? Any help would be greatly appreciated!