Hello @JKRet 

I will try to answer your question one by one:

1) Is there a general / minimum list of requirements , which criteria the local WiFi network must meet so that the TP Link can connect in client mode and establish Internet access?

Kevin: There should be no special requirements for the Wi-Fi network if you can connect your phone or laptop to that Wi-Fi. Just make sure there are no special settings on that Wi-Fi such as Access Control or MAC filtering, which may block the WR802N to connect to it.

2) What about DualBand routers in the local network? Does / should the 5GHz mode be deactivated for these? Is the TL-WR902AC an alternative solution here so that the local dual-band router does not have to be switched?

Kevin: There is no need to disable or deactivate the 5GHz mode, you can leave it enabled and connect this WR802N to the 2.4GHz, it should work. You can read this story.

3) In Range Extender mode, the TL-WR802N also works as a client. Are there special cases where the range extender mode is the better solution?

Example: I have extended a local WiFi network with a TL-WR802N (configured as a range extender) and then want to connect another TL-WR802N to it in client mode. But that didn't work - the connection was only possible when I configured the second TL-WR802N as a range extender.

Kevin: Yes, Range Extender mode is different from Client mode, you can check the story as I mentioned in Q2 also. The main difference would be you can only connect a device to the WR802N with a wired connection when it is configured in Client mode, while you can connect to it via both cable and wireless when it is in Range extender or Repeater mode.

Do you mean the following is not working?

Wi-Fi signal )))((( WR802N in Range Extender mode )))((( WR802N in Client mode

When you connect a computer to the WR802N Client, do you get the correct IP address? Be sure the IP settings on the Rance Extender and Client are configured correctly.