diff --git a/.evergreen/config.yml b/.evergreen/config.yml
index e102d42cb..3582d9702 100644
--- a/.evergreen/config.yml
+++ b/.evergreen/config.yml
@@ -859,6 +859,18 @@ functions:
           ${PREPARE_SHELL}
           ${DRIVERS_TOOLS}/.evergreen/run-load-balancer.sh stop
 
+  "tear down aws":
+    - command: shell.exec
+      params:
+        shell: "bash"
+        script: |
+          ${PREPARE_SHELL}
+          cd "${DRIVERS_TOOLS}/.evergreen/auth_aws"
+          if [ -f "./aws_e2e_setup.json" ]; then
+            . ./activate-authawsvenv.sh
+            python ./lib/aws_assign_instance_profile.py
+          fi
+
   "upload test results":
     - command: attach.xunit_results
       params:
@@ -878,6 +890,7 @@ pre:
 post:
   - func: "stop load balancer"
   - func: "stop mongo orchestration"
+  - func: "tear down aws"
   - func: "upload test results"
   - func: "upload-mo-artifacts"
   - func: "cleanup"
@@ -1019,8 +1032,8 @@ tasks:
       - func: "run aws auth test with assume role credentials"
       - func: "run aws auth test with aws credentials as environment variables"
       - func: "run aws auth test with aws credentials and session token as environment variables"
-      # - func: "run aws auth test with aws EC2 credentials"
-      # - func: "run aws ECS auth test"
+      - func: "run aws auth test with aws EC2 credentials"
+      - func: "run aws ECS auth test"
       - func: "run aws assume role with web identity test"
 
   - name: "test-5.0-standalone"
@@ -1081,8 +1094,8 @@ tasks:
       - func: "run aws auth test with assume role credentials"
       - func: "run aws auth test with aws credentials as environment variables"
       - func: "run aws auth test with aws credentials and session token as environment variables"
-      # - func: "run aws auth test with aws EC2 credentials"
-      # - func: "run aws ECS auth test"
+      - func: "run aws auth test with aws EC2 credentials"
+      - func: "run aws ECS auth test"
       - func: "run aws assume role with web identity test"
 
   - name: "test-6.0-standalone"
@@ -1143,8 +1156,8 @@ tasks:
       - func: "run aws auth test with assume role credentials"
       - func: "run aws auth test with aws credentials as environment variables"
       - func: "run aws auth test with aws credentials and session token as environment variables"
-      # - func: "run aws auth test with aws EC2 credentials"
-      # - func: "run aws ECS auth test"
+      - func: "run aws auth test with aws EC2 credentials"
+      - func: "run aws ECS auth test"
       - func: "run aws assume role with web identity test"
 
   - name: "test-7.0-standalone"
@@ -1205,8 +1218,8 @@ tasks:
       - func: "run aws auth test with assume role credentials"
       - func: "run aws auth test with aws credentials as environment variables"
       - func: "run aws auth test with aws credentials and session token as environment variables"
-      # - func: "run aws auth test with aws EC2 credentials"
-      # - func: "run aws ECS auth test"
+      - func: "run aws auth test with aws EC2 credentials"
+      - func: "run aws ECS auth test"
       - func: "run aws assume role with web identity test"
 
   - name: "test-rapid-standalone"
@@ -1267,8 +1280,8 @@ tasks:
       - func: "run aws auth test with assume role credentials"
       - func: "run aws auth test with aws credentials as environment variables"
       - func: "run aws auth test with aws credentials and session token as environment variables"
-      # - func: "run aws auth test with aws EC2 credentials"
-      # - func: "run aws ECS auth test"
+      - func: "run aws auth test with aws EC2 credentials"
+      - func: "run aws ECS auth test"
       - func: "run aws assume role with web identity test"
 
   - name: "test-latest-standalone"
@@ -1330,8 +1343,8 @@ tasks:
       - func: "run aws auth test with assume role credentials"
       - func: "run aws auth test with aws credentials as environment variables"
       - func: "run aws auth test with aws credentials and session token as environment variables"
-      # - func: "run aws auth test with aws EC2 credentials"
-      # - func: "run aws ECS auth test"
+      - func: "run aws auth test with aws EC2 credentials"
+      - func: "run aws ECS auth test"
       - func: "run aws assume role with web identity test"
 
   - name: "test-connection-string"
diff --git a/src/client/auth/aws.rs b/src/client/auth/aws.rs
index 64a4033cf..807a65f7f 100644
--- a/src/client/auth/aws.rs
+++ b/src/client/auth/aws.rs
@@ -167,7 +167,7 @@ pub(crate) struct AwsCredential {
 
     #[serde(
         default,
-        deserialize_with = "serde_util::deserialize_datetime_option_from_double"
+        deserialize_with = "serde_util::deserialize_datetime_option_from_double_or_string"
     )]
     expiration: Option<bson::DateTime>,
 }
diff --git a/src/serde_util.rs b/src/serde_util.rs
index e36f5a89b..80ac8014e 100644
--- a/src/serde_util.rs
+++ b/src/serde_util.rs
@@ -129,14 +129,29 @@ pub(crate) fn serialize_true<S: Serializer>(s: S) -> std::result::Result<S::Ok,
 }
 
 #[cfg(feature = "aws-auth")]
-pub(crate) fn deserialize_datetime_option_from_double<'de, D>(
+pub(crate) fn deserialize_datetime_option_from_double_or_string<'de, D>(
     deserializer: D,
 ) -> std::result::Result<Option<bson::DateTime>, D::Error>
 where
     D: Deserializer<'de>,
 {
-    let millis = f64::deserialize(deserializer)? * 1000.0;
-    Ok(Some(bson::DateTime::from_millis(millis as i64)))
+    #[derive(Deserialize)]
+    #[serde(untagged)]
+    enum AwsDateTime {
+        Double(f64),
+        String(String),
+    }
+
+    let date_time = match AwsDateTime::deserialize(deserializer)? {
+        AwsDateTime::Double(seconds) => {
+            let millis = seconds * 1000.0;
+            bson::DateTime::from_millis(millis as i64)
+        }
+        AwsDateTime::String(string) => bson::DateTime::parse_rfc3339_str(string)
+            .map_err(|e| serde::de::Error::custom(format!("invalid RFC 3339 string: {}", e)))?,
+    };
+
+    Ok(Some(date_time))
 }
 
 #[cfg(test)]