The 'Solutions'
1. Race Quality & Voice Chat
2. Wired vs Wireless
3. DMZ Mode
4. DNS Fix
5. MTU Size
Race Quality & Voice Chat
The 'Race Quality' option is available in-game to the person hosting the lobby. For personal lobbies it is set in your lobby options, and for public lobbies it is selected when the lobby is created. It's function is to determine how often data is sent between the players connected to a lobby. If a player cannot keep up with the rate of data transmission then they may experience lag, they may appear to lag to others, they may
cause lag for others, and they may get disconnected from the lobby.
To help those on slower connections the host can set the 'Race Quality' to either 'low' or 'very low'. That way the data transmission rate should be easier to keep up with resulting in less lag and less disconnections. Note that lowering this setting will
not necessarily affect the visual smoothness of racing for those that have no lag/connection issues. I've run two events this week, one on 'very low' and the other on 'very high', and there were no visual differences in the movement of the cars.
The voice chat feature also has various quality options as well as the ability to disable it entirely. Voice chat requires bandwidth, so you can obviously help those on slower connections by reducing the quality or turning it off. As chatting during a race is not allowed here at RD and because very few people ever use voice chat between races, it is disabled for all RD events.
Wired vs Wireless
This is the obvious one. If your PS3 is close enough to your router to use a cable, do it. A wired connection will generally be faster and more stable, which means reduced risk of lag and disconnections.
If you are definitely out of cable range then try and put your PS3 as close as physically possible to your router (or vice versa), with no obstructions between them. This will ensure that you get the best possible reception though it is still unlikely to be as stable as a wired connection. If your signal strength is continuously low then you may want to look into purchasing a better router.
DMZ Mode
Sometimes connection issues can be resolved by putting your PS3 in DMZ mode. This essentially means that your router will not attempt to block internet traffic to/from your console, preventing data loss and increasing stability. To do this you will need administrator access to your router, and you will need to give your PS3 a static IP address.
1) Start your PS3 and go to 'Network Settings' => 'Settings and Connection Status List'.
2) Make a note of the current 'IP Address', and the 'Default Router' address.
3) Now go to 'Internet Connection Settings', select 'Custom' and enter the required information until you reach the IP Address.
4) Select 'Manual' and enter the information as follows:
- IP Address: Use the first three parts of the IP address you noted down above, but add 50 to the fourth part. For example, if it was 192.168.0.10 above then change it to 192.168.0.60. Make a note of this new number too.
- Subnet Mask: Set it to 255.255.255.0.
- Default Router: Use the 'Default Router' address you noted down in step 2.
- Primary/Secondary DNS: You can also use the Default Router address here, or you could use Googles public DNS servers as described in the DNS Fix above.
5) Enter the remaining information as normal.
Now you need to log into your router as an administrator in order to change some settings. Exactly how you do this will depend on the make/model of your router. You are looking for an option that allows you to assign a DMZ. Once found you will be asked for an IP address for the DMZ. Use the new IP address you assigned to your PS3 in step 4. (192.168.0.60 in the example.) Save the settings and log out of the router.
Return to your PS3 and perform an 'Internet Connection Test'. If all was done correctly it should succeed and your NAT type will be listed as '2'. Once in GT5, remember to go to Options => Network and click 'Clear System Cache'.
Source
DNS Fix
If you get the message 'cannot connect to server' or are getting disconnected frequently, then it may be a DNS problem. A possible fix for this is to tell your PS3 to use a different DNS server. To try this, do the following:
1) Start your PS3 and go to Network Settings => Internet Connection Settings.
2) Select 'Custom' and enter the required information until you reach the DNS settings.
3) For the Primary DNS, enter 8.8.8.8
4) For the Secondary DNS, enter 8.8.4.4
5) Job done. You PS3 will now use those DNS servers.
6) Once in GT5, go into Options => Network and click 'Clear System Cache'.
Note: The addresses above are Googles public DNS servers. You could try other DNS servers if you like, though Googles have solved the issue for many people.
MTU Size
The MTU is the maximum size of data packet that can be sent by your PC/PS3. It will vary slightly between ISPs, but if your router is using an incorrect MTU it can reduce performance and stability. You can manually find your optimum MTU pinging. In order to do this you will need administrator access to your router.
1) Log into your router as administrator and find the MTU setting. If it isn't already, set it to 1500 and save.
2) Click 'Start' => 'Run' and type 'CMD' to open a command prompt. Type the following, followed by 'Enter':
3) Keep reducing the MTU by 10 until you do
not see the message "packet needs to be fragmented".
4) Now keep increasing the number by 1 until the message returns. When it does, revert to the previous MTU that worked.
5) Add 28 to this number, and you now have you optimal MTU. (eg, if the MTU that worked was 1442, your optimal MTU would be 1470.)
6) Return to your router, enter this number as the MTU and save.
Also make sure to check the MTU setting in your PS3's internet settings. You can choose to set this manually and use the same number as for your router. However, setting it to automatic should make it use this value automatically.
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