That balun is only a test - not a solution. A fact that helps identify the defect.
I do not see a list of every wire connected to the Raspberry system. Nor a description of every wire into the power supply. I do not see a description of how the Raspberry Pi digital ground connects to earth ground or even a chassis that contains it. Also which ground does the coax cable shield connect to.
Remember, even interconnected grounds are electrically different. So all grounds that connect to a Raspberry must be at a common point to avert ground currents in the Raspberry’s digital ground plane.
Forget silliness using surge protectors. Spec numbers make obvious it will do nothing. Its let-through voltage is probably 330 volts. That means it does absolutely nothing until voltage will exceeds 330 volts. A voltage that high means a Raspberry no long works.
Your symptoms are consistent with ground loop currents. If those currents, for example, pass across the Raspberry’s ground plane (called a ground loop), then the Raspberry must crash. Describe in detail how all grounds are interconnected. Only use a single point earth ground for everything. And always connect a Raspberry ground to receptacle safety ground. Verify that a connection from receptacle safety ground to earth ground is intact - measures almost zero VAC between them.
Find (or confirm it does not exist) ground loop currents. Appreciate that Raspberry’s digital ground is electrically different from wall receptacle safety ground, is different from single point earth ground, and is different from antenna ground. And all must be interconnected using methods that do not create ground loop currents.