Optimizing whole house coaxial distribution
I doubt your symptoms have much to do with inside the house, though following up the comments to look at what the modem shows (ideally capturing what it shows when you are having an outage) is a good idea. I had lots of dropouts on "Time Warner Business Class" that various service calls (with replacements of various cables - no splitters on that one, but replacing them is also "cable-guy Standard Operating Procedure")  didn't fix. One day it became evident that they had changed their central office equipment and things got a WHOLE lot better. But not perfect.

Any 2-way splitter is going to be down by at least 3 dB - that's just half power, and if it's a splitter, that's all you can get from a perfect one. The extra 0.5 dB is reality .vs. a perfect world.

Likewise, an 8-way splitter is 1-2-4-8 so it will be down by at least 9 dB from its input, which is why the amplifier is in front of it. Presumably the amplifier is not kind to your DOCSIS signals (or won't pass them upstream) which is why the modem is split off before that.