Xfinity speed fluctuating on multiple devices

Ok long story from the very beginning so someone can help me untangle this web.

One day in December last year I woke up my ethernet going unusably slow and not loading or only half loading pages, like I could try to open an Amazon page and only the top bar would load.  My brother was also unable to log into his work.  So I checked speedtest.xfinity.com and saw my wired connections were only getting 270mbps  I then tried logging into the admin page of my modem but the password didn't work.  So I tried the default password next and it worked.  Inside I could see my SSID was changed to PleasantPalms and my wifi password was changed.  I called tech support and after troubleshooting for over an hour they said they were escalating it to tier 2 and it'd be fixed by 1pm.  It was finally fixed at around 5:30pm and everything was back to normal.  
Then 2 weeks later I woke up and happened again. PleasantPalms in the SSID and unusable ethernet.  Not wanting to experience the long tech support again I tried using my xfinity app and turned on and off the wifi broadcast and it fixed it. I thought maybe some guy was hacking into my modem so I changed the password from,(just an example, not my actual password)A to B.  Then it happened again 2 weeks later in the morning.  So I went to pick up a new modem on February 2 since I figured the modem itself must be faulty and factory resetting itself.  After installing it the problem seemed to be resolved.
  Then March 19 in the morning I saw the same symptoms again, speedtest.xfinity.com was saying my ethernet was getting 270mbps and it was unusably slow and not loading or only partially loading stuff. I tried to log into the admin page and password B didn't work, neither did the default one.  I then tried password A and it let me in, despite never using password A on the new modem.  There again was SSID PleasantPalms.  Neither using the app nor power cycling fixed it.  So I called tech support and they sent a tech over.  I explained to him the history of the problem and showed him the speed.  Then he called someone at xfinity and they did something and said everything looked good on their end and it should be working now.  The SSID was still PleasantPalms and I used speedtest.xfinity.com to show them the ethernet doesn't work like it's supposed to when that happens.  Instead of 270mbps I was now at 0mbps with occasional jumps to 270.  
THIS IS WHERE I BELIEVE MY NEW PROBLEM BEGAN and the speed fluctuation was introduced, with whatever the xfinity agent on the phone did on March 19.  
Continuing from there, the person on the phone said to try the xfinity app again to save the settings, I told them it didn't work earlier and they said it was because something was set to "null" and to try it.  So I did and it loaded my previous settings.  speedtest.xfinity.com was then showing my speed at 700mbps which was lower than usual, since I'd always be at the 930mbps before, but I just wanted it over by then.  So they scheduled someone to change the outside line the next day and left.  I ran multiple speedtests at speedtest.xfinity.com after and noticed my speed would fluctuate between 450-930mbps. An hour later the modem started jumping between PleasantPalms and my usual SSID.  I called tech support and, in an odd coincidence my modem stayed on the correct SSID after calling, they said my modem was in a "yellow state" and I should change my modem asap.  I asked what that meant and they said it was fluctuating a lot and it wasn't provisioned correctly and a new modem would fix it.
  March 20 a tech came, told me his supervisor said I'd explain what he was there to do.  I told them what they told me the previous day about changing the wire leading to my house and installing a box on the wall.  So he changed the wire from the pole, and seems to have pulled a few feet of the white coax cable from the attic to get it into the box(I guess there was enough extra?), modem resets and finally stays on my SSID.  Speeds were still fluctuating between 490-930mbps but it was usable for work, I didn't notice any problem in the games I play or my browsing, and neither did my father.(my brother who uses the wifi said sometimes things don't load for him for like a minute and he also notices problems when playing yugioh Master Duel but I didn't want to deal with the stress of tech support anymore).
April 1, internet randomly cuts out during work causing my brother to drop a call(which is pretty bad and can get him fired) and we use the xfinity app which says there is a problem with the settings and it will reprovision and restart the modem.  It starts working again but I figure hey maybe we should get a new modem like the tech said as this fluctuation is probably a symptom of a bad problem which can cause disconnects.  
  So the April 2 we picked up a new modem, the old one then disconnected midwork twice with fluctuations getting down to 300mbps, and we connected and activated the new modem at night.  Not only did the new modem NOT fix the fluctuation, it introduced new problems for me.  Now when I browse it will randomly hang on loading for like 20-30seconds(same problem my brother was having).  If I interrupt it with a refresh or opening a different page in the site it won't load.  It makes me wait those 20-30 seconds and then everything in the site works normally until it randomly happens again.  My brother said it also got worse for him on youtube, twitter, and the ps5.  So I called tech support and they sent someone over on April 5.
  I showed the tech multiple pictures of the speed test at 500, 600, and 300, as well as a video of the website not loading for 30 sec while everything else did and told him my brother had a similar problem with the sites he uses. I even did a speed test in front of him showing 670mbps on ethernet. The tech said the signal outside was good, and the signal from the modem to his meter is good and the problem is in my devices. I've checked 2 phones and 2 pcs on my network and it fluctuated with all of them. 
 Like one time my speedtest with the phone next to the modem got 50mbps the entire time before jumping up to 100 at the end of the test, went to my wired computer and was getting 250mbps from the speedtest, went to the 2nd wired computer and it got 800mbps, then tried my phone again and it was getting 550-600 and the 1st pc was getting a solid 800mbps.

A few tidbits that may potentially be important:
My xfinity app says I'm getting 1200mbps to my gateway, and the tech's meter was getting 980 from the modem.
 *IMPORTANT* On March 19 at night I noticed a huge amount of devices on my gateway in the app.  According to the app they were connected by moca, even a wired camera that wasn't mine.  I blocked them all and made sure to have moca disabled (I've always had it disabled but it kept turning on with the SSID change to PleasantPalms) as soon as my settings were able to stick the next day. I've recently realized the issue with the SSID change was some kind of entanglement between my modem and my neighbor's. All this time I was thinking PleasantPalms was the factory default SSID lol. I checked and can also still see it on the list of available wifi networks.
 After the tech visit on April 5, fed up with the odd stalling I tried changing back to the previous modem and it just worked without needing to be activated(which was odd as they usually need to be reactivated after activating a new one).  The stalling problem remained and the app was showing we had no modem connected, so I changed back to the new one(which also didn't need to be reactivated)
  I've turned off the wifi on the modem and tested and the fluctuation was still there.
  After March 19 my IP location no longer shows as Ft. Myers but as Naples.
  
Thank you for reading and I hope someone can help me fix this.  Maybe check what xfinity techs did to my service on March 19 while my signal was crossed with my neighbor's.
I wrote this all around April 7 but have been putting off posting it because it's really stressful dealing with tech support.  However lately it's been acting up more with some devices getting knocked off the internet until they're restarted. I've also started getting a lot of uncorrectable codeword errors in channels 40-45