This document is about: PUN 2

PUN Classic (v1), PUN 2 and Bolt are in maintenance mode. PUN 2 will support Unity 2019 to 2022, but no new features will be added. Of course all your PUN & Bolt projects will continue to work and run with the known performance in the future. For any upcoming or new projects: please switch to Photon Fusion or Quantum.

Frequently Asked Questions

Which Photon product is the right one for me?

The answer to this depends mostly on your project and team. Generally, we suggest to use either Fusion or Quantum, which are our most advanced client solutions.

For a quick overview, both product sheets contain the product picker "Quadrant":

Additionally, this page discusses using the Photon Cloud or Photon Server?.

Feel free to reach out to us for any questions.

Photon Cloud

Is Photon Cloud down?

Our Photon Cloud Status Page shows the current and past status per product. Information about incidents is also published on twitter: @photon_status.

Is there a default Photon Cloud region?

Actually, there is no default region. Clients know the Name Server address for the Photon Cloud. They are global and used to provide an up to date region list for the given AppId.

Clients will ping each region and identify the "Best Region", which has the lowest latency.

If none of the regions can be pinged successfully, the first region of the list is used.

Can we get a list of all Cloud servers / IPs?

Such a list does not exist as the Photon Cloud is changing too frequently. Servers get added or removed and even new regions show up from time to time. This means it is impossible to add the Photon Cloud (as a whole) to an allow-list.

It is a different topic for an Enterprise Cloud. We'd discuss this via mail.

Apps within the Photon Industries Circle can rely on the host name for allow-listing: *

Is it possible to disable some regions?

Yes. It works in the other way around by defining a list of allowed regions. Read more about the "Dashboard Regions Filtering".

Load Balancing

What is the maximum number of players supported by Photon rooms?

Most Photon multiplayer games have 2-16 players, but the theoretical limit of players/peers per room can be quite high. There are Photon games live with 32 or even 64 players and in virtual conferencing scenarios it can be in the hundreds. However, sending too many messages per second (msg/s per room) can cause performance issues depending on the client's processing power coping with data. While high player numbers in e.g. turnbased games are totally fine, more than 32 players in a fast-paced action game likely will require you to implement interest management. This way not every player receives every message from all the other players.

The number of players per room is the main factor for increasing data traffic inside the game room: This is why we recommend keeping your msg/s per room count below 500. Photon does not enforce this limit, but relies on a fair use policy. Keeping an eye on your bandwidth usage is always important and it helps to ensure you stay within your plans included traffic range of 3GB per CCU.

Is there a limit for Photon strings?

Photon uses strings for lots of purposes: room name, lobby name, UserID, Nickname, custom property key, etc.

Technically, the Photon binary protocol can serialize strings up to 32767 one-byte-characters but it is strongly recommended to use the shortest strings possible.

For names and UserIDs 36 characters should be enough (e.g. a GUID is 36 characters). For custom property keys, you should use shorter strings to minimize their overhead. This is especially important for properties which are visible in the lobby, as those are part of the room lists and get sent to everyone in the lobby, not just the couple of clients in a room.

Is there a limit for the number of custom properties?

Yes, there is a limit: Each user can set 13k key-values and their total size in the room can't go over 500kB. The more Custom Properties are set, the longer the clients take to join a room, as clients receive all of the properties.

Can I send a huge message using Photon?

We do not recommend transferring large data (i.e. files) using Photon unless you know what you are doing. We advise you to optimize the data you exchange and get in touch with us if you really have to send a very big message.

Photon Cloud has a server side limit for client buffers which is 500KB. So depending on the context a message could be considered:

  • "too big" for our per client buffer size on Photon Cloud > 500KB. If a client hits this limit in a short period of time, it will be disconnected by the server.
  • "too big" to be sent with UDP without resulting in an amount of fragments that might cause problems > 100KB.
  • "too big" to be sent without splitting it up into multiple UDP packets > 1.2KB (including protocols overhead).

For messages that get sent very regularly (10 times a second or even more often) we would recommend to keep their size below 1KB.

If a message only get sent rarely (for example once at the start of a match), then a size of multiple KB is still fine, but we still would recommend to keep it below 10KB.

Larger messages can be sent in a separate Enet channel (in UDP), which affects the other channels (state sync) less.

For large files, consider using a separate backend.

Which data should be sent reliable and which should be sent unreliable?

First of all, you should know reliability is an option only when the protocol used is UDP. TCP has its own "reliability" mechanism(s) which are not covered here.

Sending something reliable means that Photon makes sure it arrives at the target client(s). So in case clients do not receive an acknowledgment within time, they will repeat sending until the acknowledgment is received or the number of resends is exceeded. Also, repeating reliable events may cause extra latency and make subsequent events delayed.

Examples for not using reliability:

  • player position updates in realtime games
  • voice or video chat (streaming)

Example for using reliability:

  • turn events in turn-based games
  • score updates that don't change rarely

Why do I have so many disconnects in my game?

The disconnects could be due to various reasons. We already have this documentation page that can help you investigate the related issues: "Analyzing Disconnects".

How messages per second per room are calculated?

Photon server counts total inbound and outbound messages every second and divide it by the total number of rooms (on the same Master Server).

Any operation request or operation response or event is considered a message. Photon operations return an optional operation response and trigger zero or more events. Cached events are also counted as messages.

Messages cost per in-room operation:

Operation Success: Best Case Success: Average Case Success: Worst Case
Create 2
+ Join event (SuppressRoomEvents=false, default)
Join 2 + k
+ k * cached custom event
2 + n + k
+ n * Join event (SuppressRoomEvents=false, default)
2 + 2 * n + k
+ n * ErroInfo event (HasErrorInfo=true)
Leave 2
1 + n
+ (n - 1) * Leave event (SuppressRoomEvents=false, default)
2 + (n - 1) * 2
+ (n - 1) * ErroInfo event (HasErrorInfo=true)
RaiseEvent 1
(no operation response)
(target: interest group with no subscribers)
1 + n
+ n * custom event
(target: all/broadcast)
2 + 2 * n
+ n * ErroInfo event (HasErrorInfo=true)
+ Auth event (token refresh)
SetProperties 2
2 + n
+ n * PropertiesChanged event (default: Broadcast=true, BroadcastPropertiesChangeToAll=true)
2 + 2 * n
+ n * ErrorInfo event (HasErrorInfo=true)
+ 1 in case of CAS or BroadcastPropsChangeToAll

How do I calculate traffic consumed by a user?

This is a complex topic. First you need to know that any calculation done is just a theoretical estimation and may not reflect reality. We recommend building a Proof-of-Concept and use it to gather real data.

That being said here is how to estimate traffic generated by a single user inside a room:

Let's assume the following:

  • a room has N players.
  • a player sends F messages per second (message send rate in Hz)
  • average message size is X (in bytes, payload (P) + protocol overhead (O))
  • an average player spends H hours per month on your game

If we do not consider ACKs, connection handling (establishment, keep alive, etc.) commands and resends. Then we say that on average, a CCU consumes C (in bytes/month) in your game as follows:

C = X * F * N * H * 60 (minutes per hour) * 60 (seconds per minute)

How to quickly rejoin a room after disconnection?

To recover from an unexpected disconnection while joined to a room, the client can attempt to reconnect and rejoin the room. We call this a "quick rejoin". A quick rejoin will succeed only if:

  • the room still exits on the same server or can be loaded: If a player leaves a room, the latter can stay alive on Photon server if other players are still joined. If the player is the last one to leave and the room becomes empty then the EmptyRoomTTL is how long it will remain alive waiting for players to join or rejoin. If after EmptyRoomTTL the room is still empty and no one joined then it will be removed from Photon server. If persistence conditions are met and webhooks are setup, the room state can be saved on the configured web service to be loaded later.
  • the actor is marked as inactive inside: an actor with the same UserId exists inside the actors' list but not currently joined to the room. This requires PlayerTTL to be different from 0.
  • the PlayerTTL for the inactive actor did not expire: when an actor leaves a room with the option to come back we save his Deactivation timestamp. As long as the room is alive, if PlayerTTL milliseconds are elapsed after Deactivation time the respective actor is removed from the actors' list. Otherwise, when the actor tries to rejoin, if the difference in milliseconds between the time of the rejoin attempt and Deactivation time exceeds PlayerTTL then the actor is removed from the actors' list and the rejoin fails. So an inactive actor can rejoin a room only for PlayerTTL milliseconds after Deactivation time.

In PUN you can call PhotonNetwork.ReconnectAndRejoin().


What is the difference between PUN Plus and PUN Free?

The content of the packages is identical but with the purchase of PUN Plus you get a voucher for a 100 CCU Photon Cloud Subscription that is valid for 12 months from the time of redeeming it.

It is a really good deal as 100 CCU are in average sufficient for 2.000 DAU and 40.000 MAU (these numbers are averages across all games that run in our Cloud).

Please note that you must redeem the code in your dashboard within 12 months after the purchase date.

How To Redeem The PUN Plus Voucher?

  1. Open your Photon Dashboard.
  2. Click -/+ CCU for the App Id you intend to apply the voucher to.
  3. Select the 100 CCU tab.
  4. Click "Got a Voucher? Add plan using your coupon code..." and enter your invoice id (not order number).
  5. Enter your Unity invoice number in the "Coupon Code or Unity Invoice No." field. You get the Unity invoice number once you purchase PUN Plus for the Unity Asset Store. Do not use the order number.
  6. Double check the application ID and Click "REDEEM".

Why Do I Have So Much Lag In My Game?

If you have infrequent ping (RTT) issues, it is hard to tell what actually happens in those cases. Aside from the game and PUN itself, it can also be related to network issues. The infrastructure is often very complex and hard to control. Some messages in PUN are reliable (e.g. RPCs) and when those get lost, they need to be resent. If this happens more than once, the ping will go up quickly and the in-game logic stalls due to lack of updates.

PUN has features to fight lag due to resends but it can't avoid it entirely. Always make sure to update to the latest version.

Lag could lead to disconnects. You can have a look at the common solutions to disconnects described here.

If you think we should take a closer look at your case, we need to know how to reproduce it, the frequency it happens with, when and for how long. Ideally, you already tried this on more than one connection and connection type and on more than one specific device - let us know on which.

Provide us the details described here.

If there is anything we can reproduce, we will try to find a solution to it.

What PUN Version Am I Using?

PUN version can be obtained in 3 different ways:

  • inside the Unity Editor, from PhotonServerSettings inspector, it's mentioned on the top.
  • from PhotonNetwork.PunVersion string field.
  • from "Assets\Photon\PhotonUnityNetworking\changelog.txt", check the first entry on top.


Do you have special offers for students, hobbyists or indies?

All our products have a free tier and a one-off entry-plan. We also usually take part in Unity's asset store sales and occasionally give vouchers to lucky ones.

Can I combine more than one 100 CCU plan for a single Photon application?

No. The 100 CCU plans are not stackable and can be applied only once per AppId. If you purchase multiple PUN+ asset seats then you must redeem each 100 free CCU for a separate AppId. If you need more CCU for a single app, the next higher plan is the 500 CCU one. If you subscribe to a monthly or yearly plan, then you will still keep the 100 CCUs for 12 months on top of / in addition to the CCU from your monthly/yearly plan.

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