diff --git a/core/services/gateway/connectionmanager.go b/core/services/gateway/connectionmanager.go
index 17a31014c81..86660f03dc9 100644
--- a/core/services/gateway/connectionmanager.go
+++ b/core/services/gateway/connectionmanager.go
@@ -87,6 +87,9 @@ func NewConnectionManager(gwConfig *config.GatewayConfig, clock utils.Clock, lgg
 				return nil, fmt.Errorf("duplicate node address %s in DON %s", nodeAddress, donConfig.DonId)
 			}
 			nodes[nodeAddress] = &nodeState{conn: network.NewWSConnectionWrapper()}
+			if nodes[nodeAddress].conn == nil {
+				return nil, fmt.Errorf("error creating WSConnectionWrapper for node %s", nodeAddress)
+			}
 		}
 		dons[donConfig.DonId] = &donConnectionManager{
 			donConfig:  &donConfig,
@@ -232,11 +235,18 @@ func (m *donConnectionManager) SetHandler(handler handlers.Handler) {
 }
 
 func (m *donConnectionManager) SendToNode(ctx context.Context, nodeAddress string, msg *api.Message) error {
+	if msg == nil {
+		return errors.New("nil message")
+	}
 	data, err := m.codec.EncodeRequest(msg)
 	if err != nil {
 		return fmt.Errorf("error encoding request for node %s: %v", nodeAddress, err)
 	}
-	return m.nodes[nodeAddress].conn.Write(ctx, websocket.BinaryMessage, data)
+	nodeState := m.nodes[nodeAddress]
+	if nodeState == nil {
+		return fmt.Errorf("node %s not found", nodeAddress)
+	}
+	return nodeState.conn.Write(ctx, websocket.BinaryMessage, data)
 }
 
 func (m *donConnectionManager) readLoop(nodeAddress string, nodeState *nodeState) {
diff --git a/core/services/gateway/connectionmanager_test.go b/core/services/gateway/connectionmanager_test.go
index f924761439a..d198ef67295 100644
--- a/core/services/gateway/connectionmanager_test.go
+++ b/core/services/gateway/connectionmanager_test.go
@@ -8,8 +8,10 @@ import (
 
 	"github.com/stretchr/testify/require"
 
+	"github.com/smartcontractkit/chainlink/v2/core/internal/testutils"
 	"github.com/smartcontractkit/chainlink/v2/core/logger"
 	"github.com/smartcontractkit/chainlink/v2/core/services/gateway"
+	"github.com/smartcontractkit/chainlink/v2/core/services/gateway/api"
 	gc "github.com/smartcontractkit/chainlink/v2/core/services/gateway/common"
 	"github.com/smartcontractkit/chainlink/v2/core/services/gateway/config"
 	"github.com/smartcontractkit/chainlink/v2/core/services/gateway/network"
@@ -208,3 +210,20 @@ func TestConnectionManager_FinalizeHandshake(t *testing.T) {
 	err = mgr.FinalizeHandshake(attemptId, response, nil)
 	require.ErrorIs(t, err, network.ErrChallengeInvalidSignature)
 }
+
+func TestConnectionManager_SendToNode_Failures(t *testing.T) {
+	t.Parallel()
+
+	config, nodes := newTestConfig(t, 2)
+	clock := utils.NewFixedClock(time.Now())
+	mgr, err := gateway.NewConnectionManager(config, clock, logger.TestLogger(t))
+	require.NoError(t, err)
+
+	donMgr := mgr.DONConnectionManager("my_don_1")
+	err = donMgr.SendToNode(testutils.Context(t), nodes[0].Address, nil)
+	require.Error(t, err)
+
+	message := &api.Message{}
+	err = donMgr.SendToNode(testutils.Context(t), "some_other_node", message)
+	require.Error(t, err)
+}
diff --git a/core/services/gateway/gateway.go b/core/services/gateway/gateway.go
index 8c77e9b7485..d64ee43233a 100644
--- a/core/services/gateway/gateway.go
+++ b/core/services/gateway/gateway.go
@@ -4,9 +4,12 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"strings"
 
 	"go.uber.org/multierr"
 
+	"github.com/ethereum/go-ethereum/common"
+
 	"github.com/smartcontractkit/chainlink/v2/core/logger"
 	"github.com/smartcontractkit/chainlink/v2/core/services/gateway/api"
 	"github.com/smartcontractkit/chainlink/v2/core/services/gateway/config"
@@ -59,6 +62,12 @@ func NewGatewayFromConfig(config *config.GatewayConfig, handlerFactory HandlerFa
 		if donConnMgr == nil {
 			return nil, fmt.Errorf("connection manager ID %s not found", donConfig.DonId)
 		}
+		for idx, nodeConfig := range donConfig.Members {
+			donConfig.Members[idx].Address = strings.ToLower(nodeConfig.Address)
+			if !common.IsHexAddress(nodeConfig.Address) {
+				return nil, fmt.Errorf("invalid node address %s", nodeConfig.Address)
+			}
+		}
 		handler, err := handlerFactory.NewHandler(donConfig.HandlerName, donConfig.HandlerConfig, &donConfig, donConnMgr)
 		if err != nil {
 			return nil, err
diff --git a/core/services/gateway/gateway_test.go b/core/services/gateway/gateway_test.go
index a6662505db0..a2ee8f7a6c0 100644
--- a/core/services/gateway/gateway_test.go
+++ b/core/services/gateway/gateway_test.go
@@ -49,6 +49,10 @@ HandlerName = "dummy"
 [[dons]]
 DonId = "my_don_2"
 HandlerName = "dummy"
+
+[[dons.Members]]
+Name = "node one"
+Address = "0x0001020304050607080900010203040506070809"
 `)
 
 	lggr := logger.TestLogger(t)
@@ -102,6 +106,24 @@ SomeOtherField = "abcd"
 	require.Error(t, err)
 }
 
+func TestGateway_NewGatewayFromConfig_InvalidNodeAddress(t *testing.T) {
+	t.Parallel()
+
+	tomlConfig := buildConfig(`
+[[dons]]
+HandlerName = "dummy"
+DonId = "my_don"
+
+[[dons.Members]]
+Name = "node one"
+Address = "0xnot_an_address"
+`)
+
+	lggr := logger.TestLogger(t)
+	_, err := gateway.NewGatewayFromConfig(parseTOMLConfig(t, tomlConfig), gateway.NewHandlerFactory(nil, lggr), lggr)
+	require.Error(t, err)
+}
+
 func TestGateway_CleanStartAndClose(t *testing.T) {
 	t.Parallel()
 
diff --git a/core/services/gateway/integration_tests/gateway_integration_test.go b/core/services/gateway/integration_tests/gateway_integration_test.go
index 7a0204a3156..310047950e6 100644
--- a/core/services/gateway/integration_tests/gateway_integration_test.go
+++ b/core/services/gateway/integration_tests/gateway_integration_test.go
@@ -6,6 +6,7 @@ import (
 	"crypto/ecdsa"
 	"fmt"
 	"net/http"
+	"strings"
 	"sync/atomic"
 	"testing"
 
@@ -110,6 +111,8 @@ func TestIntegration_Gateway_NoFullNodes_BasicConnectionAndMessage(t *testing.T)
 	t.Parallel()
 
 	nodeKeys := common.NewTestNodes(t, 1)[0]
+	// Verify that addresses in config are case-insensitive
+	nodeKeys.Address = strings.ToUpper(nodeKeys.Address)
 
 	// Launch Gateway
 	lggr := logger.TestLogger(t)