diff --git a/netbox/dcim/filtersets.py b/netbox/dcim/filtersets.py
index 8a83a8a6b..4dfb080bc 100644
--- a/netbox/dcim/filtersets.py
+++ b/netbox/dcim/filtersets.py
@@ -1197,7 +1197,9 @@ class InterfaceFilterSet(PrimaryModelFilterSet, DeviceComponentFilterSet, CableT
         label='LAG interface (ID)',
     )
     speed = MultiValueNumberFilter()
-    duplex = django_filters.CharFilter()
+    duplex = django_filters.MultipleChoiceFilter(
+        choices=InterfaceDuplexChoices
+    )
     mac_address = MultiValueMACAddressFilter()
     wwn = MultiValueWWNFilter()
     tag = TagFilter()
diff --git a/netbox/dcim/forms/filtersets.py b/netbox/dcim/forms/filtersets.py
index ab7b9785a..8868cdf78 100644
--- a/netbox/dcim/forms/filtersets.py
+++ b/netbox/dcim/forms/filtersets.py
@@ -947,10 +947,11 @@ class InterfaceFilterForm(DeviceComponentFilterForm):
         label='Select Speed',
         widget=SelectSpeedWidget(attrs={'readonly': None})
     )
-    duplex = forms.ChoiceField(
+    duplex = forms.MultipleChoiceField(
         choices=InterfaceDuplexChoices,
         required=False,
-        label='Select Duplex'
+        label='Select Duplex',
+        widget=StaticSelectMultiple()
     )
     enabled = forms.NullBooleanField(
         required=False,