Dark Souls is meant to be brutal and unforgiving, but the game's PC port may have taken that philosophy too far. The framerate cap and dodgy resolution rendering can be fixed with mods , but if you want to play co-op with a friend, things become even more complicated. That's because a combination of summoning rules, awkward P2P connections and counter-intuitive advice can make successful summoning a nightmare. Fortunately, a Steam user has collected together a complete guide to the dos and don'ts of network connection.
First, the most important advice - and something that might contradict tips you may have seen elsewhere: don't spam summon signs. Dark Souls creates a P2P IP pool every time you start the game. Spamming the sign sends out false signals to these connections, actually reducing your chance of being summoned. Even if you're not spamming the sign, there's still a chance of no connection being found or a "summoning failed" error being displayed. Here are the conditions that must be met for a successful summon:
If you're still experiencing problems, then the game's unintuitive P2P pool is acting up. It appears that connections aren't prioritised by region, meaning its entirely possible they're extending halfway across the world and causing lag. According to the guide, "You will notice that the summon sign will usually disappear within seconds after a summon attempt which fails. This works the same way with invasions. The best thing you can do is wait for the summon sign to show up again and keep trying. You will usually get the summon to work within 2-5 attempts."
The guide suggests that both you and your co-op partner leave the game open for an hour before co-op sessions, in order to maximise the IP pool. You can also use a tool like Comodo Firewall to check that the game is successfully making UDP IN and OUT connections.
Finally, if you're getting summon failed errors multiple times in a row before your partner's sign disappears, either the client or host (not both) should quit the game and retry.
All told, it's a giant hassle, but the guide claims that successfully following its instructions can result in a summoning wait of 5-10 minutes. You can read the full technical details of Dark Souls' connection issues here .