diff --git a/.changelog/31251.txt b/.changelog/31251.txt
new file mode 100644
index 00000000000..86bd2d10a83
--- /dev/null
+++ b/.changelog/31251.txt
@@ -0,0 +1,7 @@
+```release-note:enhancement
+resource/aws_fsx_ontap_file_system: Allow in-place update of `route_table_ids`
+```
+
+```release-note:enhancement
+resource/aws_fsx_ontap_file_system: Support setting `throughput_capacity` to `4096`
+```
diff --git a/internal/service/fsx/ontap_file_system.go b/internal/service/fsx/ontap_file_system.go
index 7f939f184e0..0ce57df8551 100644
--- a/internal/service/fsx/ontap_file_system.go
+++ b/internal/service/fsx/ontap_file_system.go
@@ -181,7 +181,6 @@ func ResourceOntapFileSystem() *schema.Resource {
 				Type:     schema.TypeSet,
 				Optional: true,
 				Computed: true,
-				ForceNew: true,
 				MaxItems: 50,
 				Elem:     &schema.Schema{Type: schema.TypeString},
 			},
@@ -210,7 +209,7 @@ func ResourceOntapFileSystem() *schema.Resource {
 			"throughput_capacity": {
 				Type:         schema.TypeInt,
 				Required:     true,
-				ValidateFunc: validation.IntInSlice([]int{128, 256, 512, 1024, 2048}),
+				ValidateFunc: validation.IntInSlice([]int{128, 256, 512, 1024, 2048, 4096}),
 			},
 			"vpc_id": {
 				Type:     schema.TypeString,
@@ -398,6 +397,22 @@ func resourceOntapFileSystemUpdate(ctx context.Context, d *schema.ResourceData,
 			input.OntapConfiguration.DiskIopsConfiguration = expandOntapFileDiskIopsConfiguration(d.Get("disk_iops_configuration").([]interface{}))
 		}
 
+		if d.HasChange("route_table_ids") {
+			o, n := d.GetChange("route_table_ids")
+			ns := n.(*schema.Set)
+			os := o.(*schema.Set)
+			added := ns.Difference(os)
+			removed := os.Difference(ns)
+
+			if added.Len() > 0 {
+				input.OntapConfiguration.AddRouteTableIds = flex.ExpandStringSet(added)
+			}
+
+			if removed.Len() > 0 {
+				input.OntapConfiguration.RemoveRouteTableIds = flex.ExpandStringSet(removed)
+			}
+		}
+
 		_, err := conn.UpdateFileSystemWithContext(ctx, input)
 
 		if err != nil {
diff --git a/internal/service/fsx/ontap_file_system_test.go b/internal/service/fsx/ontap_file_system_test.go
index 87b59e11eb7..999e5cbaa6e 100644
--- a/internal/service/fsx/ontap_file_system_test.go
+++ b/internal/service/fsx/ontap_file_system_test.go
@@ -284,11 +284,11 @@ func TestAccFSxOntapFileSystem_routeTableIDs(t *testing.T) {
 		CheckDestroy:             testAccCheckOntapFileSystemDestroy(ctx),
 		Steps: []resource.TestStep{
 			{
-				Config: testAccONTAPFileSystemConfig_routeTable(rName),
+				Config: testAccONTAPFileSystemConfig_routeTable(rName, 1),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckOntapFileSystemExists(ctx, resourceName, &filesystem1),
 					resource.TestCheckResourceAttr(resourceName, "route_table_ids.#", "1"),
-					resource.TestCheckTypeSetElemAttrPair(resourceName, "route_table_ids.*", "aws_route_table.test", "id"),
+					resource.TestCheckTypeSetElemAttrPair(resourceName, "route_table_ids.*", "aws_route_table.test.0", "id"),
 				),
 			},
 			{
@@ -297,6 +297,23 @@ func TestAccFSxOntapFileSystem_routeTableIDs(t *testing.T) {
 				ImportStateVerify:       true,
 				ImportStateVerifyIgnore: []string{"security_group_ids"},
 			},
+			{
+				Config: testAccONTAPFileSystemConfig_routeTable(rName, 2),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckOntapFileSystemExists(ctx, resourceName, &filesystem1),
+					resource.TestCheckResourceAttr(resourceName, "route_table_ids.#", "2"),
+					resource.TestCheckTypeSetElemAttrPair(resourceName, "route_table_ids.*", "aws_route_table.test.0", "id"),
+					resource.TestCheckTypeSetElemAttrPair(resourceName, "route_table_ids.*", "aws_route_table.test.1", "id"),
+				),
+			},
+			{
+				Config: testAccONTAPFileSystemConfig_routeTable(rName, 1),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckOntapFileSystemExists(ctx, resourceName, &filesystem1),
+					resource.TestCheckResourceAttr(resourceName, "route_table_ids.#", "1"),
+					resource.TestCheckTypeSetElemAttrPair(resourceName, "route_table_ids.*", "aws_route_table.test.0", "id"),
+				),
+			},
 		},
 	})
 }
@@ -750,7 +767,7 @@ resource "aws_fsx_ontap_file_system" "test" {
 `, rName, iops))
 }
 
-func testAccONTAPFileSystemConfig_routeTable(rName string) string {
+func testAccONTAPFileSystemConfig_routeTable(rName string, cnt int) string {
 	return acctest.ConfigCompose(testAccOntapFileSystemBaseConfig(rName), fmt.Sprintf(`
 resource "aws_internet_gateway" "test" {
   vpc_id = aws_vpc.test.id
@@ -761,6 +778,8 @@ resource "aws_internet_gateway" "test" {
 }
 
 resource "aws_route_table" "test" {
+  count = %[2]d
+
   vpc_id = aws_vpc.test.id
 
   route {
@@ -779,13 +798,13 @@ resource "aws_fsx_ontap_file_system" "test" {
   deployment_type     = "MULTI_AZ_1"
   throughput_capacity = 128
   preferred_subnet_id = aws_subnet.test1.id
-  route_table_ids     = [aws_route_table.test.id]
+  route_table_ids     = aws_route_table.test[*].id
 
   tags = {
     Name = %[1]q
   }
 }
-`, rName))
+`, rName, cnt))
 }
 
 func testAccONTAPFileSystemConfig_securityGroupIDs1(rName string) string {
diff --git a/website/docs/r/fsx_ontap_file_system.html.markdown b/website/docs/r/fsx_ontap_file_system.html.markdown
index e36dfc010a0..2cdcd187c47 100644
--- a/website/docs/r/fsx_ontap_file_system.html.markdown
+++ b/website/docs/r/fsx_ontap_file_system.html.markdown
@@ -42,7 +42,7 @@ The following arguments are supported:
 * `fsx_admin_password` - (Optional) The ONTAP administrative password for the fsxadmin user that you can use to administer your file system using the ONTAP CLI and REST API.
 * `route_table_ids` - (Optional) Specifies the VPC route tables in which your file system's endpoints will be created. You should specify all VPC route tables associated with the subnets in which your clients are located. By default, Amazon FSx selects your VPC's default route table.
 * `tags` - (Optional) A map of tags to assign to the file system. If configured with a provider [`default_tags` configuration block](https://registry.terraform.io/providers/hashicorp/aws/latest/docs#default_tags-configuration-block) present, tags with matching keys will overwrite those defined at the provider-level.
-* `throughput_capacity` - (Required) Sets the throughput capacity (in MBps) for the file system that you're creating. Valid values are `128`, `256`, `512`, `1024`, and `2048`.
+* `throughput_capacity` - (Required) Sets the throughput capacity (in MBps) for the file system that you're creating. Valid values are `128`, `256`, `512`, `1024`, `2048`, and `4096`.
 
 ### Disk Iops Configuration