Hotspot cant use in bridege mode(transparent)

hi, everybody!
My netowork topology is Firewall(DHCP)—(lan1)ROS(lan2)----Switch—AP/PC.
The first, I try building NAT+DHCP+Srcnat mode with the Hotsopt in ROS, and it‘s successfully。
But I want build a unified network that it isnt have two different network.
So, I use Bridge mode :
FIrewall(DHCP)----Bridge—Switch(L2)—PC1.
|\\\\\\\\\(lan1)(lan2)
Switch----PC2

Now, The PC1 can already visit the outside network(ex. google). And it can visit PC2.
But, The hotspot is failure. When I startup Hopspot service, i cannt connect Ros use Winbox. But The PC1 can visit the outside network, and it doesnt need hotspot authentication.

Please tell me why?
PS: please provide some suggest for me, I don’t want use nat. thank you

sover