Assistance for troubleshooting network problems
for video and/or audio conferences
(the entire route, the double arrows stand for both directions of data exchange)
Conference room <-> internet <-> internet provider (Telekom/Vodafone/UnityMedia/...) <-> own modem <-> own WLAN <-> End device ↔ Audio/Video input device
In principle, problems can occur along the entire route.
Possible problem areas and possible solutions
too many participants with picture and sound.
- only who speaks has his microphone switched on
- only who speaks has the video switched on
in times of crisis the network can simply be overloaded
- Conference start not on the full or half hour, but at alternative times
In addition to the Internet in general, a bandwidth limit may already be activated because (e.g.: mobile network) the booked data volume has been reached, or the booked connection speed to the provider is too low.
- Reduce video resolution or switch off the video completely
Here you as a user have little influence.
Usually you receive the modem/router from your provider and have almost no configuration options.
- A LAN connection (cable from the router to the end device) is preferable to a WLAN connection, as higher data transfer rates are usually achieved.
- When connecting with a LAN cable, please deactivate the WLAN on the computer.
- In the VC case, however, the latency and jitter are decisive, less the data transmission rate. Both values should be as low as possible. With cable connection they are usually lower compared to WLAN connection (see: Test possibilities of the Internet connection speed).
- If it has to be WLAN, the principle also applies here: "The closer to the router, the better the connection".
- Most newer routers transmit with two frequencies:
2.4 GHz und 5 GHz:
- 2.4 GHz has a greater range, but can become problematic if neighbouring networks in the vicinity also use their own or an adjacent channel. Here it could be helpful to start a new channel search on the router. This searches for a less used channel.
- 5 Ghz has a faster data throughput, but the range is much smaller than at 2.4 GHz, especially when walls between router and terminal have to be penetrated. The 5 GHz band is currently not as busy as the 2.4 GHz band, because especially older and cheaper end devices do not support the 5 GHz band.
- Has the device already worked in another network?
- If so, was a network administrator responsible for the device at the previous location?
- Then probably a fixed IP address has been assigned to the device in the network settings. Since in most private networks an IP address is assigned by the router (DHCP), you must change from fixed IP address to DHCP in the network settings of the terminal device
perhaps the computer is an older device and cannot cope with the performance requirements of the application.
- Switch off all unnecessary applications in the background.
- If several windows are open in the Internet browser, close the windows that are not needed.
- Check whether there is an update for the browser in use.
- It may also help to use another browser (Firefox, Chrome, Safari)
- With WebEx, the WebEx application requires less performance than the browser version.
- Determine whether the computer is at the performance limit:
- Windows PC
via the task manager (in the task bar below, right mouse button, task manager)
On the "Performance" tab, you can check the utilization of the CPU, RAM and disk.
The activity display can also be used to check the utilization of the CPU, the main memory and the hard disk.
Details can also be added using the (apple)+2, (apple)+3 and (apple)+4 shortcuts.
It is always better if you use a headset.
On the one hand, this filters ambient noise and, more importantly, there is less risk of feedback. (The sound from the speakers is again transmitted via the microphone).
Even with a mobile phone it is better to use a headset.
If possible, try to configure the headset via the computer's system settings. Only if absolutely necessary a program from the microphone manufacturer should be used.
Make sure that the input level of the microphone is not set too high. This will cause distortion and overmodulation of the sound at the other end.
If possible, a connection should be made via the operating system. Then the camera should be easily recognized by the conference software.
If you prefer to use a lower resolution (picture quality) during a conference, the picture should also be transmitted more smoothly.
Please avoid backlight situations (bright light behind the user) and ensure that your face is adequately illuminated. (A dark face against a light background is rarely helpful).
- Test your equipment before the session begins.
Feel free to start the tests 10 minutes before.
- If you don't have the floor, deactivate your microphone to avoid unwanted "babbling in".
- If there are several participants, the video should only be active for the speakers. On the one hand it is irritating if 20 faces are visible on the screen and on the other hand the conference system is unnecessarily loaded and the available bandwidth to the Internet is exceeded.
- If you would like to present slides, it may make sense to distribute them beforehand or offer a download option.
- Always have a plan B ready. Especially in times of crisis, the Internet is under great strain.
- If necessary, postpone the meeting to a pure telephone conference.
If you contact support with your problem, you should know the following in advance:
- Which Internetprovider (Vodafone, Unitymedia, Telekom, . . .)?
- Which booked connection speed?
- Connection in the house with LAN (cable) or WLAN?
- When connected with a LAN cable, is the WLAN deactivated on the computer?
- If WLAN: 2.4GHz or 5GHz?
- What kind of end device is actually used (a computer is not enough)?
- Size of the main memory?
- Which operating system (Windows (version?), MacOS, Unix/Linux)?
- Which browser is used? Firefox or Chrome in the current version are strongly recommended
- Do you use a headset?
- If so, which application causes the problem (Webex, DFNconf, jitsi, . . . )?
- Have you had better experiences with other applications?
- Have you done the speed test? - What result?
- How are download, upload, ping, jitter (see: Test possibilities of the Internet connection speed) ?
- BELWUE- Connection from the university to the home network
- Connection test for Unitymedia and Vodafone customers (with a good evaluation based on the booked data rate)
- Connection test for Telekom and other customers
If you have measurement results available, here is a small explanation:
Package loss rate
Denotes the packets that are lost between the PC and the remote terminal. Larger 5% is bad but possibly still tolerable, larger 10% is critical.
The ping refers to the time it takes a data packet from your PC to a server on the Internet - this delay is also known as latency.
A latency greater than 200ms is bad.
is the time fluctuation between the reception of two data packets. To compensate for this, a buffer slows down data reception. The jitter is often in the single-digit millisecond range, but values up to 30 ms are still normal.
A bandwidth of 1MBit (permanent) is normally sufficient for a Webex conference. This means that a higher real bandwidth is advantageous, but a smaller bandwidth makes a fluent conference almost impossible.
Communication and Information Centre (kiz)
Please contact us if you have questions or problems related to the kiz services:
Monday - Thursday
09:00 h - 12:00 h and 13:00 h - 15:30 h
Friday 09:00 h - 12:00 h
+49 (0) 731 / 50 - 30000
+49 (0) 731 / 50 - 1230000
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