Wireless Joint

Yo mymens.
I am such a dodo.
Bought this booster kit https://www.amazon.com/gp/product/B08GY ... UTF8&psc=1 .
But I can't hook up the external antenna to the indoor box because cable's ends are too thick, can't get them thru the existing hole in the wall.
I want to piggyback on an existing coax cable (for regular spectrum or comcast cable TV/internet) to get me a link from the antenna outside to indoors.
So I bought this adapter https://www.amazon.com/gp/product/B07LF ... UTF8&psc=1
which was a stupid mistake. Wrong adaptor.
Any idea what kind of female to female adaptor to buy?

So you need SMA Female to SMA Female, or N Female to N Female? Like this: https://thewirelesshaven.com/shop/rf-connectors/n ... e-adapter/

As far as antenna amplifiers/boosters, while they do in fact boost dB signal levels ("bars"), they also introduce "RF noise" which interferes with high speed data along with higher latency (ping times). Usually low end/cheap boosters (<$200) will have higher SNR (Signal to Noise Ratio), while high end more expensive (> $200) models will have lower SNR ("You get what you pay for!";).

For data purposes, a weaker un-amplified "clean signal" actually works better than an amplified/boosted "noisy signal". In other words, trying to amplify a low level signal will always give you a high level (dB), but it's going to be a low quality signal (RSQ) due to the booster's noise. Course your mileage may vary depending on many factors such as the modem, antenna, signal levels, band/frequency, multi-path propagation, and the phase of the moon (well, maybe not that last one lol).

Boosters tend to work well for voice calls, but can actually degrade your data speeds.  Having said that, try it out with and without the booster while disregarding the signal level (dB), to test which setup gives you the highest data speeds by running this simple speed test at:
https://www.bing.com/widget/t/speedtest