Received the UDP response from the required sorce to the unnecessary:iptables -t nat -I PREROUTING -i enp0s18 -p udp --dport 1235 -j DNAT --to-destination 81.хх.хх.12

The answer is that you need to set up computer clusters under the management of any Linux-like OS. Here are a few solutions that are ready:[useless link: has been removed]. http://linux.yaroslavl.ru/docs/conf/cluster.html ♪For reference: https://ru.wikipedia.org/wiki/%D0%9A%D0%BB%D0%B0%D1%81%D1%82%D0%B5%D1%80_(%D0%B3%D1%80%D1%83%D0%BF%D0%BF%D0%B0_%D0%BA%D0%BE%D0%BC%D0%BF%D1%8C%D1%8E%D1%82%D0%B5%D1%80%D0%BE%D0%B2) ♪It makes no sense to describe the whole process. I think my answer is helpful.

$ ping -I br0 10.20.1.1As far as I understand the question, you are embarrassed that this team is not working.but it should not be " working " . -I You indicated that the packages were sent through the web interface. br0And you have addresses. 10.20.1.0/24 available on interface tun0♪because$ ping 10.20.1.1 and working normally, sending over the packages the right interface.tun0Of course you can point it out and clearly:$ ping -I tun0 10.20.1.1 a To enable customers from one network to " tap " to clients from another network, and others There should be an appropriate route passing through one of your computers: either silent or exclusive to the " neighbourly " network (why should customers know where to send packages and answers to them).