bridge problems solved...

... in realtime...

echo 0 > /proc/sys/net/bridge/bridge-nf-call-iptables

... maybe check also this...

  "You need to manually `modprobe br_netfilter` to get this directory."

  @ https://askubuntu.com/questions/645638/directory-proc-sys-net-bridge-missing

... maybe make persistent... (not tested)...

@ /etc/sysctl.conf

net.bridge.bridge-nf-call-arptables = 0
net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0

net.bridge.bridge-nf-filter-pppoe-tagged = 0
net.bridge.bridge-nf-filter-vlan-tagged = 0

# sysctl -p /etc/sysctl.conf
# reboot

... otherwise, try...

@ /etc/ufw/sysctl.conf

net/bridge/bridge-nf-call-arptables = 0
net/bridge/bridge-nf-call-ip6tables = 0
net/bridge/bridge-nf-call-iptables = 0

# reboot