I run pfSense+ firewall and an nxFilter (ad blocker for network) in a virtual machine on a TS-453Be (90% of the time this architecture has been fine) and since upgrading to QTS 5.2.6.3195 I was dealing with incredibly slow performance and high cpu loads both on my NAS and in the virtual machine [and on my entire network]. I am sure if I checked, QNAP temps were likely raised as well. Speed Tests both through my network, from the firewall itself, and ssh’d into the QNAP were about 1/8th of my usual. My Eero wireless mesh devices run a test every night at the same time and after the first night showed a drop from an average 629Mbps/627Mbps down to around 80/72. Process monitoring did show a good number of never-ending python processes, so could be related. Like others, I resolved by downgrading back to QTS 5.2.5.3145. Despite the strong “this is not supported” messaging thankfully the revert process was successful. I’d encourage QNAP to consider officially supporting the downgrading process within MAJOR version for some reasonable # of hops as unexpected, untenable issues can arise and take some time to troubleshoot which requires someone to find an interim solution beyond waiting for a future release to address that issue.
I notice QTS firmware update is now advising I am on the latest version, so I suspect QNAP has recognized the issues with 5.2.6.3195 and pulled it. I don’t see anything in the change log that glaringly stands out as potentially causing so potentially just some technical debt refactoring led us here. I’ll likely keep a look out on the forums for the good news that the next version doesn’t have similar issues before upgrading or at bare minimum wait some time before I upgrade in the future. Cheers