How to redirect traffic through an intermediate server to the main one and back?

Question

linux

we have two servers...
intermediate: XXXX, which stands under the QQQQ.QQQQQ.QQ domain and main: YYYY, on which Outline vpn stands. It is
necessary to redirect traffic through the intermediate server to the main one and back.

I do this:
echo 1 > /proc/sys/net/ipv4/ip_forward

iptables -A INPUT -m state --state NEW -m tcp -p tcp --dport XXX -j ACCEPT

iptables -t nat -A PREROUTING -p tcp -d XXXX --dport XXX -j DNAT --to-destination YYYY:YYYYY

iptables -t nat -A POSTROUTING -p tcp --dst YYYY --dport YYYYY -j SNAT --to-source XXXX

Now in the outline key:
ss://[email protected]:XXXXX/?outline=1
I'm changing the IP address and port:
ss://[email protected]:XXX/?outline=1
and everything works...
but when I write QQQQ.QQQQQ.QQ instead of XXXX in the key, the key no longer works...
meanwhile QQQQ.QQQQQ.QQ pings normally as XXXX

I'm sorry if it's crumpled and without any details. Written on a spiritual uplift and courage.