gRPC Issues for GetAccountAtBlockHeight

Another gRPC error unknown is on my end or server-side:

GetAccountAtBlockHeightRequest addressReq1 = new GetAccountAtBlockHeightRequest
            {
                Address = ByteString.CopyFrom(HexStringToByteArray("0xead892083b3e2c6c")),
                BlockHeight = 18666607,
            };
AccountResponse addressResponse1 = client.GetAccountAtBlockHeight(addressReq1);

Throwing:

Status(StatusCode="Unavailable", Detail="upstream connect error or disconnect/reset before headers. reset reason: connection termination