Once again, thank you all for your advices. And once again I configured router. Hopefully now good 
# 2025-04-22 17:55:37 by RouterOS 7.18.2
# software id = 9LCG-S59P
#
# model = RB4011iGS+
/interface bridge
add name=bridge1
/interface pppoe-client
add add-default-route=yes disabled=no interface=ether1 name=pppoe-out1 \
use-peer-dns=yes user={user}
/interface list
add name=WAN
add name=LAN
/ip pool
add name=dhcp_pool0 ranges=192.168.88.2-192.168.88.254
/ip dhcp-server
add address-pool=dhcp_pool0 interface=bridge1 name=dhcp1
/port
set 0 name=serial0
set 1 name=serial1
/interface bridge port
add bridge=bridge1 interface=ether2
add bridge=bridge1 interface=ether3
add bridge=bridge1 interface=ether4
add bridge=bridge1 interface=ether5
add bridge=bridge1 interface=ether6
/interface list member
add interface=pppoe-out1 list=WAN
add interface=ether1 list=WAN
add interface=bridge1 list=LAN
add interface=ether3 list=WAN
add interface=ether4 list=WAN
add interface=ether5 list=WAN
add interface=ether6 list=WAN
/ip address
add address=192.168.88.1/24 interface=bridge1 network=192.168.88.0
add address=91.220.222.78/24 interface=ether1 network=91.220.222.0
/ip dhcp-server network
add address=192.168.88.0/24 dns-server=1.1.1.1 gateway=192.168.88.1
/ip dns
set servers=1.1.1.1
/ip firewall filter
add action=accept chain=input comment=\
"defconf: accept established,related,untracked" connection-state=\
established,related,untracked
add action=drop chain=input comment="defconf: drop invalid" connection-state=\
invalid
add action=accept chain=input comment="defconf: accept ICMP" protocol=icmp
add action=accept chain=input comment=\
"defconf: accept to local loopback (for CAPsMAN)" dst-address=127.0.0.1
add action=accept chain=input comment="user and admin access" \
in-interface-list=LAN
add action=drop chain=input comment="drop all else"
/ip firewall nat
add action=masquerade chain=srcnat out-interface-list=WAN
Any firewall rules that I should be add (or anything else) are appreciated.