Not true at all. Find the wall in the attic, drill into it, dangle your Ethernet in the wall, cut a hole for one of these reach in there and grab it out.
Hardest part is routing it in the hot attic under the insulation
I wouldn’t call it a “keystone” jack, since that seems to connote a standard size. This seems some other RJ45 modular jack variant, like the Pass & Seymour modular jacks installed at my sister’s place.
Regardless of what it is (vs it’s function), yes, it may be responsible for the Internet issues if the jack was poorly terminated or the terminations have loosened over time … which seems entirely possible.
I’d recommend replacing it with an actual keystone RJ45 jack and modular faceplate, possibly in combination with installing a low voltage bracket.
There are many styles like this. The "flap" in the back spins and tightens the box in place via two screws.
Cmple - Low Voltage Mounting Bracket 1 Gang Multipurpose Drywall Mounting Wall Plate Bracket – Single Gang https://www.amazon.com/dp/B003ZWJGGE/ref=cm_sw_r_apan_i_K5X2E3QDDV8NJRBDDPE2?_encoding=UTF8&psc=1
I assume that's what you were talking about. I was going to run an ethernet cable from the router to the office, the outlet. Then the shorter cable to complete the internet connection.
Assuming you have drywall walls, why not just install an old work 1 gang electrical box or low voltage box like these?
Cmple - Low Voltage Mounting Bracket 1 Gang Multipurpose Drywall Mounting Wall Plate Bracket – Single Gang https://www.amazon.com/dp/B003ZWJGGE/ref=cm_sw_r_apan_glt_i_NP6DYPSNW99RYS8H9NXX?_encoding=UTF8&psc=1
Absolutely. Drill a hole alongside the phone cable (carefully) and tie a nail to a string to drop it down thru the partition. Once you have the string in hand, tie it to the cable and pull (either down from the attic or up from the room). Cut a hole in the wall below and use a "low voltage" bracket (like this: https://smile.amazon.com/gp/product/B003ZWJGGE/ref=oh_aui_search_detailpage?ie=UTF8&psc=1) to hold the faceplate for the coax connection.
Anytime you run an ethernet cable through the wall, you will want to have a low voltage bracket like this:
https://www.amazon.com/Cmple-Voltage-Mounting-Bracket-Multipurpose/dp/B003ZWJGGE/
Find your stud and drill a 1” or so hole to one side of it (big enough to put your cord through). Directly below that put a pass through box in (so you’ll cut out a rectangular hole for a normal junction box. I’ve put examples below of the first things that came up on my phone. You should be able to drop the cable through the small hole and reach into the bigger hole (before installing the pass through) to pull the cable out. Then you plug it in normally and you have an easy pass through if you ever want to replace them or move.
Please continue to bug me if this is unclear.
Pass through plate
Pass through box
Cmple - Low Voltage Mounting Bracket 1 Gang Multipurpose Drywall Mounting Wall Plate Bracket – Single Gang https://www.amazon.com/dp/B003ZWJGGE/ref=cm_sw_r_cp_api_glt_fabc_FQD35QBZYB4FE09Z7VCM?_encoding=UTF8&psc=1
The RPS is a matter of preference. I use a couple of APC branded UPS units with the network expansion cards. The Ubiquiti one just ties in with everything else since it's the same ecosystem and will look the same. I use them to power my NAS units and everything tied to the network (VoIP device, switches, router, home automation bridge, modem, DNS, etc), and devices talk to the UPS via SNMP to kind of know when to shut themselves down. Having battery backup is great for those random 5-120 second power outages when working from home.
You won't need a PoE injector if your device is powered by the PoE switch.
Where to place your network devices is hard for us to say. It will create noise due to the cooling fans. And it generates heat so you can't just close it up in a closet without thinking about airflow. Many folks use their basements (I do, too), but it's not uncommon to use areas under stairs or again closets as long as you think about airflow. Putting them in an attic or garage is almost never going to work due to the ambient temperatures getting above the operating temps of the hardware. You have to figure out how cables route around your home to get where you want to go, and no one on the internet can tell you this. Mine is a combination of in the walls, across the attic, and pulled through ceilings.
Cabling running outside should be inside conduit if at all possible, but they make outdoor/UV protected CAT6 for this purpose.
You'll need wall plates, single-gang retrofit boxes (https://www.amazon.com/Cmple-Voltage-Mounting-Bracket-Multipurpose/dp/B003ZWJGGE), keystones, a punchdown tool, something to cut drywall, maybe fiberglass rods to push cables around, nylon string/thin rope to pull things, electrical tape to attach cables to rods (doesn't leave sticky residue, holds well, and is cheap). You didn't really mention if you were going to pull cables for some more wall outlets around the house too, but I assume you'd like you hardwire your TVs to get things off wifi if possible.
You would be better served to run a ethernet cable from the router (in the office) to your room. If you wanted, you could put a new wifi AP there. BUt still you should have a hard line.
Most people complain about how it cant be done, but if you or your folks own the home, believe me it can be done... do you have a basement, crawlspace or an attic? If the answer to any of those quetions is yes, then that is how you run the wire (in that order of easy-ness).
Get one of these https://www.amazon.com/Low-Voltage-Bracket-Single-Gang/dp/B003ZWJGGE/ref=sr_1_2?ie=UTF8&qid=1500570873&sr=8-2&keywords=low+voltage+wall+box then fish the wire either down to the basement or crawl space (or up to the attic), then run across to your room. Install another one, then fish the line down. Then get one of these for each https://www.amazon.com/Black-Point-Products-BT-192-White/dp/B005MPVVMY/ref=sr_1_6?ie=UTF8&qid=1500570949&sr=8-6&keywords=low+voltage+wall+plate+cat5 along with https://www.amazon.com/iMBAPrice-Female-Keystone-Coupler-IMBA-C6KC-WT-1PK/dp/B00BJP0LUE/ref=pd_sim_60_5?_encoding=UTF8&pd_rd_i=B00BJP0LUE&pd_rd_r=BW6284QVMSACA9647P97&pd_rd_w=gs2Vt&pd_rd_wg=Kjepz&psc=1&refRID=BW6284QVMSACA9...
use quad shield cat5e or cat6 cable and you will be good to go.