To reconnect to an OPC UA server we use the SessionReconnectHandler.BeginReconnect method. We specify a reconnectPeriod of 1000ms. However the reconnect fails just after 1000ms, then the OPC UA client waits about a minimum of 100ms to continue with another reconnect attempt. So it seems that the reconnectPeriod includes the time it takes to attempt the connection. The problem with this is that the OPC UA server becomes overloaded with connection requests and keeps taking too long to accept any connections. See the following log:

[11:40:36.109 VRB] CreateSession Called. RequestHandle=1, PendingRequestCount=1 <s:Opc.Ua>
[11:40:36.109 INF] ChannelId 0: in Connecting state. <s:Opc.Ua>
[11:40:37.144 VRB] CreateSession Completed. RequestHandle=1, PendingRequestCount=-2147483648, StatusCode=0 <s:Opc.Ua>
[11:40:37.144 VRB] ChannelId 0: Close <s:Opc.Ua>
[11:40:37.145 INF] ChannelId 0: in Closed state. <s:Opc.Ua>
[11:40:37.145 INF] ChannelId 0: CLIENTCHANNEL SOCKET CLOSED: FFFFFFFF <s:Opc.Ua>
[11:40:37.158 ERR] Could not reconnect the Session. Could not recreate session. Limosa OPC UA TimeManager Client <s:Opc.Ua>
[11:40:37.268 VRB] CreateSession Called. RequestHandle=1, PendingRequestCount=1 <s:Opc.Ua>
[11:40:37.268 INF] ChannelId 0: in Connecting state. <s:Opc.Ua>
[11:40:38.303 VRB] CreateSession Completed. RequestHandle=1, PendingRequestCount=-2147483648, StatusCode=0 <s:Opc.Ua>
[11:40:38.304 VRB] ChannelId 0: Close <s:Opc.Ua>
[11:40:38.305 INF] ChannelId 0: in Closed state. <s:Opc.Ua>
[11:40:38.305 INF] ChannelId 0: CLIENTCHANNEL SOCKET CLOSED: FFFFFFFF <s:Opc.Ua>
[11:40:38.317 ERR] Could not reconnect the Session. Could not recreate session. Limosa OPC UA TimeManager Client <s:Opc.Ua>

Is there any way to increase this minimum of 100ms without increasing the reconnectPeriod?

Using OPCFoundation.NetStandard.Opc.Ua.Client v1.4.371.41 on .Net 7