diff --git a/openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c b/openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c
index 30d3999f75..4af16aa199 100644
--- a/openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c
+++ b/openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c
@@ -324,6 +324,12 @@ static int handle_ue_context_drbs_setup(NR_UE_info_t *UE,
     AssertFatal(drb->qos_choice == F1AP_QOS_CHOICE_NR, "only NR QoS supported\n");
     f1ap_drb_setup_t *resp_drb = &(*resp_drbs)[i];
     NR_RLC_BearerConfig_t *rlc_BearerConfig = get_bearerconfig_from_drb(drb, rlc_config);
+    if (UE->capability && UE->capability->rlc_Parameters && UE->capability->rlc_Parameters->ext2
+        && UE->capability->rlc_Parameters->ext2->am_WithLongSN_RedCap_r17 == NULL) {
+      *rlc_BearerConfig->rlc_Config->choice.am->dl_AM_RLC.sn_FieldLength = NR_SN_FieldLengthAM_size12;
+      *rlc_BearerConfig->rlc_Config->choice.am->ul_AM_RLC.sn_FieldLength = NR_SN_FieldLengthAM_size12;
+    }
+
     nr_rlc_add_drb(UE->rnti, drb->id, rlc_BearerConfig);
 
     nr_lc_config_t c = {.lcid = rlc_BearerConfig->logicalChannelIdentity, .nssai = drb->nr.nssai};
@@ -649,6 +655,8 @@ void ue_context_setup_request(const f1ap_ue_context_setup_req_t *req)
   resp.gNB_DU_ue_id = UE->rnti;
 
   NR_CellGroupConfig_t *new_CellGroup = clone_CellGroupConfig(UE->CellGroup);
+  // Needed for DRB Setup (e.g., RLC might reduce SN size)
+  UE->capability = ue_cap;
 
   if (req->srbs_len > 0) {
     resp.srbs_len = handle_ue_context_srbs_setup(UE, req->srbs_len, req->srbs, &resp.srbs, new_CellGroup, &mac->rlc_config);
@@ -665,7 +673,6 @@ void ue_context_setup_request(const f1ap_ue_context_setup_req_t *req)
   }
 
   NR_ServingCellConfigCommon_t *scc = mac->common_channels[0].ServingCellConfigCommon;
-  UE->capability = ue_cap;
   if (ue_cap != NULL && cg_configinfo == NULL) {
     // store the new UE capabilities, and update the cellGroupConfig
     // only to be done if we did not already update through the cg_configinfo
diff --git a/openair2/RRC/NR/nr_rrc_defs.h b/openair2/RRC/NR/nr_rrc_defs.h
index 804657e8ce..68a83c9545 100644
--- a/openair2/RRC/NR/nr_rrc_defs.h
+++ b/openair2/RRC/NR/nr_rrc_defs.h
@@ -169,6 +169,13 @@ typedef enum {
   RRC_UECAPABILITY_ENQUIRY,
 } rrc_action_t;
 
+typedef struct nr_redcap_ue_cap {
+  bool support_of_redcap_r17;
+  bool support_of_16drb_redcap_r17;
+  bool pdcp_drb_long_sn_redcap_r17;
+  bool rlc_am_drb_long_sn_redcap_r17;
+} nr_redcap_ue_cap_t;
+
 /* forward declaration */
 typedef struct nr_handover_context_s nr_handover_context_t;
 
@@ -253,6 +260,7 @@ typedef struct gNB_RRC_UE_s {
   int max_delays_pdu_session;
   bool ongoing_pdusession_setup_request;
 
+  nr_redcap_ue_cap_t *redcap_cap;
 } gNB_RRC_UE_t;
 
 typedef struct rrc_gNB_ue_context_s {
diff --git a/openair2/RRC/NR/rrc_gNB.c b/openair2/RRC/NR/rrc_gNB.c
index a6ba6f8cda..ae4d55cae7 100644
--- a/openair2/RRC/NR/rrc_gNB.c
+++ b/openair2/RRC/NR/rrc_gNB.c
@@ -117,6 +117,34 @@ typedef struct deliver_ue_ctxt_release_data_t {
   sctp_assoc_t assoc_id;
 } deliver_ue_ctxt_release_data_t;
 
+const NR_RedCapParameters_r17_t *get_redcapparam_r17(NR_UE_NR_Capability_t *UE_Capability_nr)
+{
+  if (UE_Capability_nr && UE_Capability_nr->nonCriticalExtension && UE_Capability_nr->nonCriticalExtension->nonCriticalExtension
+      && UE_Capability_nr->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+      && UE_Capability_nr->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+      && UE_Capability_nr->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+             ->nonCriticalExtension
+      && UE_Capability_nr->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+             ->nonCriticalExtension->nonCriticalExtension
+      && UE_Capability_nr->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+             ->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+      && UE_Capability_nr->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+             ->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+      && UE_Capability_nr->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+             ->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+      && UE_Capability_nr->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+             ->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+             ->nonCriticalExtension
+      && UE_Capability_nr->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+             ->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+             ->nonCriticalExtension->redCapParameters_r17) {
+    return UE_Capability_nr->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+        ->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension->nonCriticalExtension
+        ->nonCriticalExtension->redCapParameters_r17;
+  } else
+    return NULL;
+}
+
 static void rrc_deliver_ue_ctxt_release_cmd(void *deliver_pdu_data, ue_id_t ue_id, int srb_id, char *buf, int size, int sdu_id)
 {
   DevAssert(deliver_pdu_data != NULL);
@@ -1590,6 +1618,18 @@ static void handle_ueCapabilityInformation(gNB_RRC_INST *rrc, gNB_RRC_UE_t *UE,
           UE->UE_Capability_nr = 0;
         }
 
+        const NR_RedCapParameters_r17_t *redcap_p = get_redcapparam_r17(UE->UE_Capability_nr);
+        if (redcap_p) {
+          UE->redcap_cap = calloc_or_fail(1, sizeof(*UE->redcap_cap));
+          UE->redcap_cap->support_of_redcap_r17 = redcap_p->supportOfRedCap_r17 != NULL;
+          UE->redcap_cap->support_of_16drb_redcap_r17 = redcap_p->supportOf16DRB_RedCap_r17 != NULL;
+          if (UE->UE_Capability_nr->pdcp_Parameters.ext2)
+            UE->redcap_cap->pdcp_drb_long_sn_redcap_r17 = UE->UE_Capability_nr->pdcp_Parameters.ext2->longSN_RedCap_r17 != NULL;
+          if (UE->UE_Capability_nr->rlc_Parameters && UE->UE_Capability_nr->rlc_Parameters->ext2)
+            UE->redcap_cap->rlc_am_drb_long_sn_redcap_r17 =
+                UE->UE_Capability_nr->rlc_Parameters->ext2->am_WithLongSN_RedCap_r17 != NULL;
+        }
+
         UE->UE_Capability_size = ue_cap_container->ue_CapabilityRAT_Container.size;
         if (eutra_index != -1) {
           LOG_E(NR_RRC, "fatal: more than 1 eutra capability\n");
@@ -2200,6 +2240,8 @@ static void rrc_delete_ue_data(gNB_RRC_UE_t *UE)
   ASN_STRUCT_FREE(asn_DEF_NR_MeasResults, UE->measResults);
   FREE_AND_ZERO_BYTE_ARRAY(UE->ue_cap_buffer);
   free_MeasConfig(UE->measConfig);
+  free(UE->redcap_cap);
+  UE->redcap_cap = NULL;
 }
 
 void rrc_remove_ue(gNB_RRC_INST *rrc, rrc_gNB_ue_context_t *ue_context_p)
diff --git a/openair2/RRC/NR/rrc_gNB_radio_bearers.c b/openair2/RRC/NR/rrc_gNB_radio_bearers.c
index 5112029f87..d91c866cd4 100644
--- a/openair2/RRC/NR/rrc_gNB_radio_bearers.c
+++ b/openair2/RRC/NR/rrc_gNB_radio_bearers.c
@@ -85,12 +85,19 @@ drb_t *get_drb(gNB_RRC_UE_t *ue, uint8_t drb_id)
 void set_default_drb_pdcp_config(struct pdcp_config_s *pdcp_config,
                                  int do_drb_integrity,
                                  int do_drb_ciphering,
-                                 const nr_pdcp_configuration_t *default_pdcp_config)
+                                 const nr_pdcp_configuration_t *default_pdcp_config,
+                                 const nr_redcap_ue_cap_t *redcap_cap)
 {
   AssertError(pdcp_config != NULL, return, "Failed to set default PDCP configuration for DRB!\n");
   pdcp_config->discardTimer = encode_discard_timer(default_pdcp_config->drb.discard_timer);
-  pdcp_config->pdcp_SN_SizeDL = encode_sn_size_dl(default_pdcp_config->drb.sn_size);
-  pdcp_config->pdcp_SN_SizeUL = encode_sn_size_ul(default_pdcp_config->drb.sn_size);
+  if (redcap_cap && redcap_cap->support_of_redcap_r17 && !redcap_cap->pdcp_drb_long_sn_redcap_r17) {
+    LOG_I(NR_RRC, "UE is RedCap without long PDCP SN support: overriding PDCP SN size to 12\n");
+    pdcp_config->pdcp_SN_SizeDL = NR_PDCP_Config__drb__pdcp_SN_SizeDL_len12bits;
+    pdcp_config->pdcp_SN_SizeUL = NR_PDCP_Config__drb__pdcp_SN_SizeUL_len12bits;
+  } else {
+    pdcp_config->pdcp_SN_SizeDL = encode_sn_size_dl(default_pdcp_config->drb.sn_size);
+    pdcp_config->pdcp_SN_SizeUL = encode_sn_size_ul(default_pdcp_config->drb.sn_size);
+  }
   pdcp_config->t_Reordering = encode_t_reordering(default_pdcp_config->drb.t_reordering);
   pdcp_config->headerCompression.present = NR_PDCP_Config__drb__headerCompression_PR_notUsed;
   pdcp_config->headerCompression.NotUsed = 0;
@@ -145,7 +152,7 @@ drb_t *generateDRB(gNB_RRC_UE_t *ue,
       est_drb->status = DRB_ACTIVE;
   }
   /* PDCP Configuration */
-  set_default_drb_pdcp_config(&est_drb->pdcp_config, do_drb_integrity, do_drb_ciphering, pdcp_config);
+  set_default_drb_pdcp_config(&est_drb->pdcp_config, do_drb_integrity, do_drb_ciphering, pdcp_config, ue->redcap_cap);
 
   drb_t *rrc_drb = get_drb(ue, drb_id);
   DevAssert(rrc_drb == est_drb); /* to double check that we create the same which we would retrieve */