TS-420 frequently runs very slow

[rosery]

Hi
I have a TS-420 running 4.3.3.1386. It has a 3 disk raid 5 setup running file sharing to mac and pc. For a long while this has behaved very satisfactorily, but for the last few months it tends to get very slow and unresponsive for most of the working day. Power cycling may give a few hours of good behaviour, then it reverts to this misbehaviour.
Disks all suggest they ar e fine (smart, etc) and the filesystem and raid are clean
Can anyone shed light on this?

[dolbyman]

was the nas exposed to wan ?

[rosery]

basically no, though there is 1 obscure port for remote admin.. port forwarded from router, and no obviuos signs of abuse of that port.

[dolbyman]

QTS Admin is the most abused part (besides all those multimedia stations) , changing the default port does not really help

so check your system for infections malware

[rosery]

Good thought, but already done. Also there are no signs of unexpected traffic via this port