Only 10 till 11 devices are possible

Hi, I can only add 10, sometimes 11 devices to my eWeLink with Sonoff Bridge Pro (v1.8). I tested it with two Sonoff Bridges because I thought the bridge is broken, but no change. After 11 devices I can’t add an additional.
I have the eWeLink advanced plan.

What can I do?

Zigbee devices?

Assuming it is there is a limit to the number of directly connected end-devices. You could add a router device but with two you could turn one of them into a router for the other one by putting Tasmota on it.

Wrong link. That is how to install coordinator firmware. This is simpler.

Yes Zigbee devices. But it can’t be that just 10 devices are passive with the zigbee bridge. I will not flash and set up a raspi eg to solve the issue.
It is sad to double the costs.

From sonoff support
ZB Bridge-P can connect 26 sub-devices directly (10 end devices + 16 routers, or 26 routers). If you want to add more than 10 end devices, routers are required.

Router: S40 Lite ZB smart plug, S31 Lite ZB smart plug, S26R2ZB smart plug,ZBMINI smart switch

End Device: ZBMINI-L smart switch, SNZB-01 switch, SNZB-02 Temp. and Hum. sensor, SNZB-03 motion sensor, SNZB-04 door/window sensor