Unstable onnection using RT-AC88U with WLAN repeaters

[Rooby]

Hi all

I have big trouble when using an RT-AC88U (380.68) with WLAN repeaters to connect a printer which has only LAN to the 2,4GHZ WLAN of the router. The repeaters I’m using are the FRITZ!WLAN Repeater 1750E and DVBC. Both repeaters are quite similar and I have the same issues.
The Problem is that the access to the repeater and the printer behind the repeater is very unstable. For some minutes have access and some minutes later I cannot ping them anymore and later I get access gain.
Both repeater have a good Wifi connection and the LEDs show that they are always connected. Also I could not find any entries in their logs. I need fix IP addresses for the repeater and the printer behind. Therefore I tested two configs:

1. Set repeater and printer to get IP addresses via DHCP and manually assign the IPs in the router.

2. Configure the repeater and printer to fix address but also leave the same IPs in the manually assign list in the router.

But I have trouble with both configs and spent lots of hours to find the issue. Here are now my questions:

Has someone similar issues or experience with (this) repeaters?

How should I do the configs to get fix IPs?

Is there any setting in the router which could lead to instabilities?


Thanks