Complaint / Escalation Requested - 100% Packet Loss - Exactly Every 15 Minutes (For about 5 seconds)

Hello,

I have an issue that started happening about a month ago and everything was fine for the first 5 months of service. Like the subject says, I am getting massive ping spikes or basically 100% packet loss at every 15 minutes intervals, throughout the day, everyday. It's definitely NOT random. I have numerous pingplotter graphs that show this, and attached is one of them. I can also time this with the exact moments I experience this. Whether I'm on a zoom call, gaming, browsing the internet etc. everything will just stop for about 5 seconds. For example, during a zoom call for work, I will be talking, and then at exactly 3h:15m:15s, my video cuts out and the recipient will have missed everything I said during the 5 second spike. If I'm gaming, I'll be clicking to move and then at 8h:45m:15s, none of my inputs will go through and then after 5 seconds, be in a completely different spot in the game.

1st cs rep said it's a "pass-through" problem. Didn't work. 2nd cs rep, I explained everything and said it probably requires a new modem installation. Tech came and through no fault of his own, didn't even know it was troubleshooting. He thought it was a fresh install. I showed the tech all the issues, even played my actual game in front of him and showed the 100% packet loss happening at the exact times. Didn't work. 3rd cs rep, started going down the "pass-through" problem again, and I said already tried and didn't work. I have another tech appointment which I have to pay $149 now, but don't feel confident that this person can or will try to help. I'll try to keep my hopes up, but hoping I can at least get this escalation started here too.

Below are a couple of details that may help, and reasons why I believe it's more of a wiring/connection issue within the apartment complex I live at. I'm not an SME with all of this for sure, but I also am not someone who doesn't know the difference between a modem and a router. And sincere apologies if I sound rude or demanding. Tbh, I am just frustrated at the lack of escalation this has gotten so far as this problem directly affects my meeting heavy schedule and is just simply annoying while gaming.

-This affects every device in my apartment unit. Mac, PC, etc. and all at the same exact time.

-I have ran pingplotter through only a wired connection straight to the modem, disconnected all routers, all devices except the one testing the connection, etc.

-Tested specific routers, specific devices, and all have the same issues. As I mentioned above, I don't think it's an isolated problem because even with a wired connected straight to the modem is still happens; and regardless of the device.

-Happened with both the old modem AND the new modem. Old modem actually worked fine for the first 5 months.

-Here's something unique. The old modem was actually directly connected to my bedroom ethernet jack. I had fiber service, but I stupidly had it connected by ethernet to the wall. I don't even know how it was connected in the small compartment in the closet. But funny enough, after the 1st tech came, the new "Fiber" modem is now in the compartment and connected by a fiber cable. Unfortunately the issue is still happening. 

-Every 15 minutes, i.e. (1:00:15, 1:15:15, 1:30:15, 1:45:15, 2:00:15, etc.) for 5 seconds roughly.

-I found a few other individuals in other forums who were having very similar issues. One person ended up solving it by actually moving to a different ISP and NOT fiber. I wonder if this has to do with the fiber connection and something happening behind the walls, in which I can't do anything about.

Appreciate anyone's help, many thanks!