RelayControl 

Namespace: SynicSugar.P2P
Class: p2pConfig

public RelayControl relayControl = RelayControl.AllowRelays;

    public enum RelayControl {
        /// <summary>
        /// Peer connections will never attempt to use relay servers. Clients with restrictive NATs may not be able to connect to peers.
        /// </summary>
        NoRelays, 
        /// <summary>
        /// Peer connections will attempt to use relay servers, but only after direct connection attempts fail. This is the default value if not changed.
        /// </summary>
        AllowRelays, 
        /// <summary>
        /// Peer connections will only ever use relay servers. This will add latency to all connections, but will hide IP Addresses from peers.
        /// </summary>
        ForceRelays
    }

Description 

Set the way to connection.
AllowRelay is default. In default, if the connection can be made directly, users connect by p2p; if it fails NAT Punch through, users use Relay(AWS) for the connection.
Users with settings NoRelay and ForceRelays cannot connect.
If we switch this value, set this before matchmaking or on Editor. If so, the library automatically switches relay setting just before conenction.
SetRelayControll could be called before matching, but since SynicSugar duplicates the switching process before connecting, it may be better to change this value directly.

using SynicSugar.P2P;

public class p2pConfigManager {
    void Setp2pConfig(){
        p2pConfig.Instance.relayControl = RelayControl.ForceRelays;
    }
}