diff --git a/coordinator/coordinator.lua b/coordinator/coordinator.lua
index fa065ce..4374b3c 100644
--- a/coordinator/coordinator.lua
+++ b/coordinator/coordinator.lua
@@ -250,7 +250,10 @@ function coordinator.comms(version, nic, wl_nic, sv_watchdog)
 
     -- switch the current active NIC
     ---@param act_nic nic
-    function public.switch_nic(act_nic) nic = act_nic end
+    function public.switch_nic(act_nic)
+        public.close()
+        nic = act_nic
+    end
 
     -- try to connect to the supervisor if not already linked
     ---@param abort boolean? true to print out cancel info if not linked (use on program terminate)
diff --git a/reactor-plc/plc.lua b/reactor-plc/plc.lua
index a630570..f7f92b9 100644
--- a/reactor-plc/plc.lua
+++ b/reactor-plc/plc.lua
@@ -830,7 +830,10 @@ function plc.comms(version, nic, reactor, rps, conn_watchdog)
 
     -- switch the current active NIC
     ---@param act_nic nic
-    function public.switch_nic(act_nic) nic = act_nic end
+    function public.switch_nic(act_nic)
+        public.close()
+        nic = act_nic
+    end
 
     -- reconnect a newly connected reactor
     ---@param new_reactor table
diff --git a/rtu/backplane.lua b/rtu/backplane.lua
index 990c0df..92289b5 100644
--- a/rtu/backplane.lua
+++ b/rtu/backplane.lua
@@ -136,7 +136,7 @@ function backplane.attach(type, device, iface, print_no_fp)
                 -- switch back to preferred wired
                 _bp.act_nic = wd_nic
 
-                comms.switch_nic(_bp.act_nic)
+                comms.switch_nic(_bp.act_nic, _bp.smem.rtu_state)
                 log.info("BKPLN: switched comms to wired modem (preferred)")
             end
         elseif wl_nic and (not wl_nic.is_connected()) and m_is_wl then
@@ -152,7 +152,7 @@ function backplane.attach(type, device, iface, print_no_fp)
                 -- switch back to preferred wireless
                 _bp.act_nic = wl_nic
 
-                comms.switch_nic(_bp.act_nic)
+                comms.switch_nic(_bp.act_nic, _bp.smem.rtu_state)
                 log.info("BKPLN: switched comms to wireless modem (preferred)")
             end
         elseif wl_nic and m_is_wl then
@@ -227,14 +227,14 @@ function backplane.detach(type, device, iface, print_no_fp)
                 elseif wd_nic and wd_nic.is_connected() then
                     _bp.act_nic = wd_nic
 
-                    comms.switch_nic(_bp.act_nic)
+                    comms.switch_nic(_bp.act_nic, _bp.smem.rtu_state)
                     log.info("BKPLN: switched comms to wired modem")
                 end
             elseif wl_nic and wl_nic.is_connected() then
                 -- wired active disconnected, wireless available
                 _bp.act_nic = wl_nic
 
-                comms.switch_nic(_bp.act_nic)
+                comms.switch_nic(_bp.act_nic, _bp.smem.rtu_state)
                 log.info("BKPLN: switched comms to wireless modem")
             else
                 -- wired active disconnected, wireless unavailable
diff --git a/rtu/rtu.lua b/rtu/rtu.lua
index 2c4c9d4..fa9908f 100644
--- a/rtu/rtu.lua
+++ b/rtu/rtu.lua
@@ -359,7 +359,11 @@ function rtu.comms(version, nic, conn_watchdog)
 
     -- switch the current active NIC
     ---@param act_nic nic
-    function public.switch_nic(act_nic) nic = act_nic end
+    ---@param rtu_state rtu_state
+    function public.switch_nic(act_nic, rtu_state)
+        public.close(rtu_state)
+        nic = act_nic
+    end
 
     -- unlink from the server
     ---@param rtu_state rtu_state