diff --git a/.env.test b/.env.test
index 31222f7549cb..6dd87a441199 100644
--- a/.env.test
+++ b/.env.test
@@ -1,13 +1,16 @@
 # We use these images during sim and e2e tests
-# TODO: Upgrade Geth once the Nethermind issue is resolved else it's causing following error
-# Rejected peer  id=134e2c1a76745626 addr=192.168.0.3:9052 conn=staticdial err="useless peer"
-GETH_DOCKER_IMAGE=ethereum/client-go:v1.11.6
+# This is the last version which supports pre/post merge chains in the same network
+# All newer versions only work with post merge chains
+GETH_DOCKER_IMAGE=ethereum/client-go:v1.13.14
 # Use either image or local binary for the testing
 GETH_BINARY_DIR=
 LIGHTHOUSE_DOCKER_IMAGE=sigp/lighthouse:v4.6.0-amd64-modern-dev
+
 # We can't upgrade nethermind further due to genesis hash mismatch with the geth
 # https://github.com/NethermindEth/nethermind/issues/6683
+# Disabling Nethermind from sim tests until the above issue is resolved
 NETHERMIND_DOCKER_IMAGE=nethermind/nethermind:1.18.2
+
 # We mostly use mainnet for unit testing
 # Changing this value may impact the tests which are written with mainnet in mind
 LODESTAR_PRESET=mainnet
diff --git a/.github/workflows/test-sim.yml b/.github/workflows/test-sim.yml
index 6895c74c016e..0a00777bfeca 100644
--- a/.github/workflows/test-sim.yml
+++ b/.github/workflows/test-sim.yml
@@ -165,7 +165,7 @@ jobs:
         run: |
           docker pull ${{env.GETH_DOCKER_IMAGE}}
           docker pull ${{env.LIGHTHOUSE_DOCKER_IMAGE}}
-          docker pull ${{env.NETHERMIND_DOCKER_IMAGE}}
+          # docker pull ${{env.NETHERMIND_DOCKER_IMAGE}}
       - name: Sim tests mixed client
         run: DEBUG='${{github.event.inputs.debug}}' yarn test:sim:mixedclient
         working-directory: packages/cli
diff --git a/packages/cli/test/scripts/e2e_test_env.ts b/packages/cli/test/scripts/e2e_test_env.ts
index b5fa48260194..9884a5a83374 100644
--- a/packages/cli/test/scripts/e2e_test_env.ts
+++ b/packages/cli/test/scripts/e2e_test_env.ts
@@ -25,7 +25,7 @@ const env = await SimulationEnvironment.initWithDefaults(
   },
   [
     {id: "node-1", beacon: BeaconClient.Lodestar, execution: ExecutionClient.Geth, keysCount: 32, mining: true},
-    {id: "node-2", beacon: BeaconClient.Lodestar, execution: ExecutionClient.Nethermind, keysCount: 32},
+    {id: "node-2", beacon: BeaconClient.Lodestar, execution: ExecutionClient.Geth, keysCount: 32},
   ]
 );
 
diff --git a/packages/cli/test/sim/multi_fork.test.ts b/packages/cli/test/sim/multi_fork.test.ts
index d816e0ddae54..f57d3a397955 100644
--- a/packages/cli/test/sim/multi_fork.test.ts
+++ b/packages/cli/test/sim/multi_fork.test.ts
@@ -76,7 +76,7 @@ const env = await SimulationEnvironment.initWithDefaults(
           },
         },
       },
-      execution: ExecutionClient.Nethermind,
+      execution: ExecutionClient.Geth,
       keysCount: 32,
       remote: true,
     },
@@ -93,7 +93,7 @@ const env = await SimulationEnvironment.initWithDefaults(
           },
         },
       },
-      execution: ExecutionClient.Nethermind,
+      execution: ExecutionClient.Geth,
       keysCount: 32,
     },
     {
@@ -110,7 +110,7 @@ const env = await SimulationEnvironment.initWithDefaults(
           },
         },
       },
-      execution: ExecutionClient.Nethermind,
+      execution: ExecutionClient.Geth,
       keysCount: 32,
     },
     {id: "node-5", beacon: BeaconClient.Lighthouse, execution: ExecutionClient.Geth, keysCount: 32},
diff --git a/packages/cli/test/utils/simulation/execution_clients/geth.ts b/packages/cli/test/utils/simulation/execution_clients/geth.ts
index 4c1b8196ab17..18e73ddba195 100644
--- a/packages/cli/test/utils/simulation/execution_clients/geth.ts
+++ b/packages/cli/test/utils/simulation/execution_clients/geth.ts
@@ -130,6 +130,7 @@ export const generateGethNode: ExecutionNodeGenerator<ExecutionClient.Geth> = (o
         `extip:${address}`,
         "--authrpc.jwtsecret",
         jwtsecretFilePathMounted,
+        "--nodiscover",
         "--datadir",
         rootDirMounted,
         "--allow-insecure-unlock",