Have a nice time :)

Again, no one is using these versions anymore.

Take pfSense from here : https://www.pfsense.org/download/ - you can trust that site as its the author.

It's 2.7.2.

Both systems have captive portal working just fine and the first one (2.6.0) runs with 2500 clients flawlessly.... The problem i noticed is if i try to apply any in/out limiters on any other interface than captive portal runs..

On version 2.7.1 which also runs captive portal on a same specs network, limiters are working just fine. I am trying to be up to date but for a hotel as you mentioned i avoid updates during on-season periods as updates could also lead to a disaster sometimes...

So normally if i update the 2.6.0 system, it should work...

I have all the recommended patches applied...

Euh ... imho your wrong.
There was a patch that came out a year or so ago, the completely overhauled the captive portal firewall internally.
Me, for example, I completely forgot about the "how did 2.6.0 captive portal work ?" (these days its all done with "pf", "ipfw", the firewall used for earlier version of pfSense, has been abandoned.
2.6.0 uses ipfw.
2.6.0 worked just fine for me (for a hotel) but I can't remember the small details, though.
There is some one who does : the forum (and you) : If you want to stay with an 'old' version, you have to 'auto support' yourself as the rest goes along with actual version.

So : it's time you patch your system.
Why did you mention 2.7.0 ??? Where did you find that ? fact check here : https://www.pfsense.org/download/

Also an update, tried on a similar setup same hardware but on version 2.7.0 and there it works fine even with captive portal.. so should i suspect a version bug? I have all the recommended patches applied...

Your pfSense version ?