Out of the box, the TVS-H1288X doesn’t seem to have TB3 ports, so it looks like yours has a TB3 card installed.
I haven’t used this one, the 1288x. But I have a smaller one QNAP TS-453BT3. It has one 10GigE port, 4x GigE ports and 2 TB3 ports.
I routinely use it with my iMac Pro and a MacBook Pro both connected to the TB3 ports. Its pretty fast, as fast as a 4-bay RAID can be. If one system writes while the other is reading, they both slow down. Same if both are reading large files. But if both my systems are editing ProResLT or DNxHD36, the system happily ‘serves’ them both simultaneously.
So, your 1288x will work much faster since it has 8 drives.
But you will see more reliable performance with systems connected to the 1288x over 10GigE or 2.4 GigE than you will see over TB3.
The 4x 2.5GigE ports, let out connect 4 systems with 2.5GigE adapters on each, and you could expect to be able to do 150 MB/sec on each simultaneously.
The TB3 ports can be used to connect to systems that are place physically close to the unit.
Also, you have 4x 2.5″ bays where you could place 4x SSDs and make them available as cache files or sources/targets for large files like DPX or OpenEXR.
Neil