Hi All,

I'm looking for some problem-solving advice... I'm trying to debug a performance issue, here:

I've got this setup working on my sailboat (see attached diagram) where I use the Groove A 52ac mounted up high, to connect to marina wifi and get an IP address, and then use that to provide a local hotspot (powered by the MikroTik RB951UI) inside the relatively small cabin of the boat. The basic affordance is that it offers smartphones and other small devices (Roku, Firestick) inside the cabin to reliably access marina wifi that's otherwise too weak to be used by these small devices.

Here's my performance issue:
1. When I connect my MacBook pro directly to say, OnSpot5G, google's speed test tells me I'm getting >20Mbps download speed.
2. When I connect the same MacBook pro to the local "Jiblet" wifi, which is the connected via ethernet to the Groove, which is then connected to the same OnSpot5G wifi, the same speed test is sucking wind at more like 5Mbps download speed. I don't understand the likely culprit for the degradation in speed, here.

My questions include,
a) how would you go about troubleshooting?
b) is 100ft of cat6 with PoE too long or somehow problematic?
c) how far away from one another would you want the Groove and the RB951UI in a scenario like this?
d) what tools or mechanisms would you use with this setup to measure/detect RF interference and select the appropriate channel on the RB951UI/Jiblet?
e) what would you think is more likely to be problematic here: misconfiguration of one of these two devices vs. RF interference?

Thanks in advance for any advice or counsel you can provide!

PS, just a note about me -- I'm a software engineer, but still learning about networking, wifi, RF, electrical engineering and other related technical endeavors.

Related to point "d" above, wondering if it's true that I should strive to select only Channels 1, 6 or 11 for my 2.4 GHz network? Here's the article that suggested it to me... What do you think?