cable recommendation please from router to wall?

What about the cable from the junction box to your house? What about the wiring in the modem/router? Probably should change capacitors and other parts too while you're at it. 😐

Lots of variables outside your control?  What's in your walls, splitters, what's outside where the ISP comes into the home.  That being said you cant control those and assuming its all good just make sure to use Cat 6 instead of Cat 5 for best performance.

As long as it is RG-6 solid copper quad shield with a hi-def compression fitting approved by DirecTVfor their installers to use. A store bought cable is likely bogus. Cable techs usually have the good compression fittings, but not always. DirecTV has a high rate of post-op inspection, so their contractors are less likely to skimp on the materials they supply. DirecTV employees are issued quality fittings for free. If you have cable and your installer was a contractor, your installer might have used copper coated aluminum for your coax runs anywhere he knows an inspection won’t happen. They don’t do nearly as many inspections as DirecTv and the fittings really are stupidly expensive. DirecTV also requires all fittings to be changed on preexisting cables used in a system that installer is signing his name to. Same on service calls. Call and ask for your system’s wiring and connectors to be inspected. You should also have an HD barrel present in your cable’s wall plate connector. The visible color inside your barrel ends should be blue. The inner copper wire should not be cut exactly at or below the end of the compression fitting. You should be able to slightly hurt yourself tapping on the business end any coax cable that is not plugged in. If you can tap on the end of it without feeling the wire picking your finger it’s not installed correctly. 

If you want to spend some money to move the ball forward, consider a linear power supply on your router instead of worrying about coax or Ethernet cable.  For a pretty good Ethernet cable at a reasonable price, consider these (link).

Note the seller’s warning about the shielded Cat8 Ethernet cables:

“* This highly double shielded wires may not work with some non-10G equipment which cause “Antenna Effect” bottlenecking network speed (down to less than 100mbps).”