lib/pleroma/web/mastodon_api/websocket_handler.ex

@@ -64,6 +64,10 @@ defmodule Pleroma.Web.MastodonAPI.WebsocketHandler do
 
   # We only receive pings for now
   def websocket_handle(:ping, state), do: {:ok, state}
+  def websocket_handle({:text, "ping"}, state) do
+    if state.timer, do: Process.cancel_timer(state.timer)
+    {:reply, {:text, "pong"}, %{state | timer: timer()}}
+  end
 
   def websocket_handle(frame, state) do
     Logger.error("#{__MODULE__} received frame: #{inspect(frame)}")