I tried to connect squid3 in my network to use high anonymity proxy. This is how my network is right now

 WAN LINK
     |
 -------------           -----------------------------
| Mikrotik Box |        |   Ubuntu Server with squid3 |
 -------------           -----------------------------
     |                 /
     |               /
 ----------------------
| Switch ( Cheap one ) |
 ----------------------
  |         |        |       
Client1  Client2  Client3   etc.

after this setup I changed squid.conf in Ubuntu server as

1. http_port 8080

2. acl localhost src xxx.xxx.xxx.xxx(Ubuntu server IP)

3. acl to_localhost dst xxx.xxx.xxx.xxx(Mikrotik router gateway) I assume that redirected http from Mikrotik router will be redirect again to Mikrotik router.

4. uncomment access log /var/log/squid3/access.log

5. add visible_hostname myname

save squid.conf and restart squid3 server.

Then I have added nat rule in Mikrotik router

ip/firewall/nat

1.  add chain=dstnat src_address=xxx.xxx.xxx.xxx(ununtu server IP) dst-port=80 protocol=tcp action=accept

2. add chain=dstnat src_address=xxx.xxx.xxx.xxx/28(LAN address) dst-port=80 protocol=tcp action=dst-nat to-address=xxx.xxx.xxx.xxx(ununtu server IP) to-port=8080

now I can not able to access internet from client1 system, If I remove these two nat rule then I can access internet. what is wrong I have made?