NetworkAgent::use_legacy_network is only meant to be an intention of whether user wants to use legacy plugin or not, anything that actually interact with the plugin should use the loaded plugin version instead.

src/slic3r/Utils/BBLNetworkPlugin.cpp

@@ -79,7 +79,7 @@ int BBLNetworkPlugin::initialize(bool using_backup, const std::string& version)
 
     // Auto-migration: If loading legacy version and versioned library doesn't exist,
     // but unversioned legacy library does exist, copy it to versioned format
-    if (version == BAMBU_NETWORK_AGENT_VERSION_LEGACY) {
+    if (is_legacy_version(version)) {
         boost::filesystem::path versioned_path;
         boost::filesystem::path legacy_path;
 #if defined(_MSC_VER) || defined(_WIN32)
@@ -162,12 +162,15 @@ int BBLNetworkPlugin::initialize(bool using_backup, const std::string& version)
     // Load all function pointers
     load_all_function_pointers();
 
-    // Sync legacy network flag from NetworkAgent (set during GUI_App initialization)
-    m_use_legacy_network = NetworkAgent::use_legacy_network;
+    // Sync legacy network flag from loaded plugin
+    m_use_legacy_network = is_legacy_version(version);
 
     std::string loaded_version;
     if (m_get_version) {
         loaded_version = m_get_version();
+        if (!loaded_version.empty()) {
+            m_use_legacy_network = is_legacy_version(loaded_version);
+        }
     }
 
     BOOST_LOG_TRIVIAL(info) << "BBLNetworkPlugin::initialize: legacy_mode="
@@ -208,6 +211,8 @@ int BBLNetworkPlugin::unload()
 
     clear_all_function_pointers();
 
+    m_use_legacy_network = false;
+
     return 0;
 }
 
@@ -377,7 +382,7 @@ bool BBLNetworkPlugin::versioned_library_exists(const std::string& version)
 
     if (boost::filesystem::exists(path)) return true;
 
-    if (version == BAMBU_NETWORK_AGENT_VERSION_LEGACY) {
+    if (is_legacy_version(version)) {
         return legacy_library_exists();
     }