After I changed my ISP (from DSL to cable) I needed a WLAN-Bridge to be able to connect my computer, printer, etc. to the new wireless modem because the connection is now in another room. During my research I found this awesome project and I was able to install the firmware on an old fritz box (7330 SL). I configured my router with the help of this article. Surprisingly this worked flawless. But after some time I noticed infrequent connection issues. I think that I can narrow it down to the relayd service, because during the connection issue
- the web frontend is still reachable over the wlan of the wireless modem (IP: 192.168.0.150)
- the web frontend is still reachable over the client subnet of the fritz box (IP: 192.168.1.1)
But every client behind the wlan bridge using the subnet of the wireless modem (192.168.0.1/24) has no connection at all. Therefore I'm guessing it is the relayd service which fails somehow.
Hopefully someone can help me to fix this issue. I haven't found any log from relayd, so I don't have the slightest idea how I should begin 
Edit: Before someone asks why I haven't choose the static route option, the wireless modem has no setting for it.