diff --git a/src/xpra/server/server_base.py b/src/xpra/server/server_base.py
index 3c0442e3a5..aa75d9297d 100644
--- a/src/xpra/server/server_base.py
+++ b/src/xpra/server/server_base.py
@@ -60,6 +60,8 @@
 SAVE_PRINT_JOBS = os.environ.get("XPRA_SAVE_PRINT_JOBS", None)
 CLIENT_CAN_SHUTDOWN = envbool("XPRA_CLIENT_CAN_SHUTDOWN", True)
 TERMINATE_DELAY = envint("XPRA_TERMINATE_DELAY", 1000)/1000.0
+AUTO_BANDWIDTH_PCT = envint("XPRA_AUTO_BANDWIDTH_PCT", 80)
+assert AUTO_BANDWIDTH_PCT>1 and AUTO_BANDWIDTH_PCT<=100, "invalid value for XPRA_AUTO_BANDWIDTH_PCT: %i" % AUTO_BANDWIDTH_PCT
 
 
 class ServerBase(ServerCore):
@@ -1196,6 +1198,15 @@ def drop_client(reason="unknown", *args):
             self.disconnect_client(proto, reason, *args)
         def get_window_id(wid):
             return self._window_to_id.get(wid)
+        bandwidth_limit = self.bandwidth_limit
+        if bandwidth_limit is None:
+            pinfo = proto.get_info()
+            socket_speed = pinfo.get("socket", {}).get("speed")
+            if socket_speed:
+                #auto: use 80% of socket speed if we have it:
+                bandwidth_limit = socket_speed*AUTO_BANDWIDTH_PCT//100 or 0
+            else:
+                bandwidth_limit = 0
         ServerSourceClass = self.get_server_source_class()
         ss = ServerSourceClass(proto, drop_client,
                           self.idle_add, self.timeout_add, self.source_remove,
@@ -1206,7 +1217,7 @@ def get_window_id(wid):
                           self.window_filters,
                           self.file_transfer,
                           self.supports_mmap, self.mmap_filename,
-                          self.bandwidth_limit,
+                          bandwidth_limit,
                           self.av_sync,
                           self.core_encodings, self.encodings, self.default_encoding, self.scaling_control,
                           self.sound_properties,
diff --git a/src/xpra/server/server_core.py b/src/xpra/server/server_core.py
index 517acd1019..cb741a46c5 100644
--- a/src/xpra/server/server_core.py
+++ b/src/xpra/server/server_core.py
@@ -209,7 +209,7 @@ def init(self, opts):
         self.session_name = opts.session_name
         set_name("Xpra", self.session_name or "Xpra")
 
-        self.bandwidth_limit = parse_with_unit("bandwidth-limit", opts.bandwidth_limit) or 0
+        self.bandwidth_limit = parse_with_unit("bandwidth-limit", opts.bandwidth_limit)
         self.unix_socket_paths = []
         self._socket_dir = opts.socket_dir or opts.socket_dirs[0]
         self.encryption = opts.encryption
@@ -1555,7 +1555,7 @@ def up(prefix, d):
                    "sockets"        : self.get_socket_info(),
                    "encryption"     : self.encryption or "",
                    "tcp-encryption" : self.tcp_encryption or "",
-                   "bandwidth-limit": self.bandwidth_limit,
+                   "bandwidth-limit": self.bandwidth_limit or 0,
                    })
         up("network", ni)
         up("threads",   self.get_thread_info(proto))