First, it would be really useful if we knew what device you're working with. It would appear to be x86 or a RPi or similar, but without details we cannot know for sure what is going on. We'll also need to know what kind of network cards are in use here and if you've loaded the appropriate drivers (if necessary).
Next, there is no need to have a bridge on the wan. The device under the wan interface should just use eth1 directly. Delete br-wan.
I also see that you have the wan interface setup as dhcp, but you have a netmask specified. Delete that line, as it shouldn't be there.
After making the two changes, restart your device and see if the lan comes up (btw, what is connected to eth0 and how is it configured)?
UPD: Topic can be closed, guys. Thank you for all your support. I really appreciate it, for it is most tolerant and friendliest community in dark and evil waves of unholy Internet.
The thing is that I've found Elitegroup 945GCT-M2 in a garbage can and the miracle happen - Integrated Network Card in this baseboard is based on THE SAME Realtek chip like discrete Network Card Gembird NIC-R1. Everithing works fine now. You're breathtaking Cheers.
I edited config several times and rebooted every time after it. Because it happen that /etc/init.d/network reload is not always work properly, only reboot helps.
Now config looks like
config interface 'loopback'
option device 'lo'
option proto 'static'
option ipaddr '127.0.0.1'
option netmask '255.0.0.0'
config globals 'globals'
option ula_prefix 'fd11:d566:7bd7::/48'
config device
option name 'br-lan'
option type 'bridge'
list ports 'eth0'
config interface 'lan'
option device 'br-lan'
option proto 'static'
option ipaddr '192.168.4.1'
option netmask '255.255.255.0'
option ip6assign '60'
config device
option name 'br-wan'
option type 'bridge'
list ports 'eth1'
config interface 'wan'
option device 'br-wan'
option proto 'dhcp'
# option netmask '255.255.255.0'
Everything is working ok. Many Thanks! I try to remove br-wan option but in reseult I unded up with no connections at all, only interfaces were listed in ifconfig