Setting the MTU of a virtual Switch on a qNAP NAS (QTSHero OS)

For a project that I am currently working for, I bought a QNAP NAS (TVS-h1288X). In that project, I have multiple network cameras. On the NAS, I have a Windows 10 VM which is supposed to store all the video recorded by those cameras. The traffic generated by those cameras is huge (up to 1 Gbit per camera), hence, they require Jumbo Frames to send the video at the full frame rate. As I read on the internet, all network equipment involved needs to support Jumbo Frames and have them enabled. As far as I can see, I enabled them on all Switches and NICs that are between the cameras and the VM, but sill, packets are dropped if I set the packet size on the cameras too high.

In order to connect the Windows 10 VM to my network, I created a "Virtual Switch" on the QNAP NAS which includes both 10 Gbit NICs on the NAS and all but 1 of the 2.5 Gbit NICs on the NAS (see network architecture diagram below) and I have a feeling that this "virtual switch" is the broken link in the chain. When I go to "Network and virtual Switch" on the NAS, then on "Interfaces", then on the 3 dots next to one the 10 Gbit NICs, then on "Configure", the Jumbo Frame size selected here is 9000 (See screenshot 1 below). But when I go to "Network and virtual Switch" -> "Virtual Switch" -> 3 dots next to the virtual Switch -> "Information" -> "Hardware" it says that the MTU is still 1500 (See screenshot 2).

Since this panel only shows information and does not allow to modify it, my question is: How can I change the MTU of the virtual switch?

Screenshot 1:

Screenshot 2:

Network architecture:

Note concerning the network architecture: I am fully aware that the direct link that the Windows 10 VM has to the internet is a security risk, but rest assured: The entire setup is currently sitting in my office and is still protected by the company firewall. Once deployed, this link will be disabled.

The virtual switch derives it's MTU size from the physical NICs that are involved. In my case, the 10 Gbit NICs were set to an MTU of 9000, but the other 2.5 Gbit NICs were set to 1500, hence, the swicth also used 1500 as its MTU. To increase it, I deleted the virtual switch and then I went to the settings of all participating NICs and set their MTU to 9000 by going to "Network and virtual Switch" -> "Interfaces" -> 3 dots next to the interface -> "Configure" -> "Jumbo Frame Size".

After that, I recreated the virtual switch and it now has an MTU of 9000.