Synology NAS supports multi-LAN, allowing you to combine those LAN interfaces using the Link Aggregation technology. Link Aggregation increases the bandwidth of your Synology NAS by aggregating multiple network interfaces and provides traffic failover to maintain network connection in case the connection is down.

Adaptive Load Balancing: This mode optimizes the network traffic received and sent by Synology NAS devices regardless of whether Link Aggregation is enabled or not. To avoid unexpected circumstances, do not enable Link Aggregation even though it is supported.

Link Aggregation (LACP) will allow you to increase the bandwidth TO and FROM your Synology NAS. In summary, this will allow more clients to send data to and from your NAS without decreased performance. To be clear, this will not double the network speed for a single client.