i have web proxy setting like this :
enabled: no
src-address: y.y.y.y
port: 8080
hostname: "proxy.problem.com"
transparent-proxy: yes
parent-proxy: 0.0.0.0:0
cache-administrator: "obby@problem.com"
max-object-size: 4096KiB
cache-drive: secondary-master
max-cache-size: unlimited
max-ram-cache-size: unlimited
status: stopped
reserved-for-cache: 56876032KiB
reserved-for-ram-cache: 2048KiB

with access : src-address=x.x.x.x/29 action=allow
with NAT :
chain=dstnat src-address=x.x.x.x/29 protocol=tcp dst-port=80
action=redirect to-ports=8080

at other side i have another mikrotik that want used proxy from ip y.y.y.y
then i make firewall nat at x.x.x.x with this rule :

chain=dstnat protocol=tcp dst-port=80 action=netmap
to-addresses=y.y.y.y to-ports=0-65535

but now i have problem, user behind mikrotik x.x.x.x can't browsing any more with that rule. when i put ip y.y.y.y at internet explorer proxy setting
there is no problem, it's mean web proxy server work well. need advice please.

regards.