Sometimes, even after clicking Allow when BitDefender Firewall notifies you about a certain application requesting access to internet, that certain application cannot connect to the internet, or has limited connectivity.
This can mostly be noticed in case of Peer to Peer clients (oDC, StrongDC++, torrent downloaders, etc...), but this behavior can also appear in other applications.
Why this happens:
BitDefender Firewall comes with two pre-defined sets of rules (one for Trusted network and one for Untrusted network). Based on your choice in the Firewall Wizard, one of those sets is, by default, applied. These sets contain rules that block some ports, considered unsafe, and which might be used by certain malware to access your computer without your knowledge. In other words, those rules are made to protect your computer.
But, sometimes, a legit application needs to use a port that is blocked by default.
The rules in BitDefender Firewall are stored ordered by their priority. The highest the position, the highest the priority. This means that if the first rule in the list blocks the port X, then the rules that are below cannot access that port, even if, apparently, they offer full access.
Solution:
Given the above, the solution to give an application 100% full access to the network is to move it's rule at the top of the list (so no other rule blocks any ports for it).
This is done quite easily. First of all, go to
BitDefender Security Center -> Settings -> Firewall -> Traffic
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There, click the Edit Profile button:
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You will see two lists, Inbound and Outbound, which contain the Firewall rules. Those lists can be sorted using the directional buttons (for each list): Move to top, Move to bottom, Move one up, Move one down
In both lists, search for the rule that needs full access, select it, and click Move to top:
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After that, click OK, and you're done. That application has now complete, 100% full access to the network.
Warning! You shouldn't change the order (or other settings) of the predefined rules. Nothing stops you to do it, but if you change them you might experience unwanted behavior.
Also, you shouldn't move all rules to the top, because this represents a security hazard (to some degree). Move to the top of the list only the applications that need access to ports that are blocked, by default, by BitDefender firewall.