Downlink frame-counter (network)* can not +1

[tluwill]

• The issue is present in the latest release.
• I have searched the issues of this repository and believe that this is not a duplicate.

What happened?

Downlink frame-counter (network) can not add . FCNT_down can not+1 ,so the

What did you expect?

Steps to reproduce this issue

Steps:

1. OTAA Joined
2. send a uplink fame to make applicatoin session key be same as endponit's applicaton session key
   3.add a BASE64 CODE in Application/Application_ubantu/Device/ MyDeviceName ,MyDeviceName is my endpoint 's name
3. uplink's framecount + ,can add 1,every tx , but donlink's framecount can not add ,always 0, so my endpoint filter the downlink frame

Could you share your log output?

Your Environment

Component	Version
Application Server	v3.17.6
Network Server	v3.16.2
Gateway Bridge	v3.13.3
Chirpstack API	WEB GUI
Geolocation	CN470
Concentratord	P-NUCLEO-LRWAN3