Intermittent Internet Outages

I have been having intermittent internet outages going on for at least the last 4 weeks or so. Once it started happening, I went ahead and replaced my wireless router and my modem. Neither have resolved the issue. I have a Roku connected via an ethernet cable. When the internet goes down, so does the Roku. 

My modem is a Hitron CODA56 and my router is a TP Link Tri Band BE9300 (Archer BE550). When the internet goes out, I check the Cox app to check for outages and it always says that my "network looks good". It's currently set up as a dynamic IP with smart connect enabled. OFDMA/MU-MIMO is also disabled. I don't have a MLO network and don't have a IoT network. Also have a TP-Link AC1200 WiFi Extender (RE315). 

Also went to the my laptop's device manager and unchecked "allow this computer to turn off this device to save power" button. 

I've also had 3 service calls. First guy checked the internet in the house with his tool, and said it was working fine. Second guy went into my crawlspace and replaced a bunch of barrel connectors. Third guy replaced the line from the telephone pole to my house. None of these resolved the issue. 

I'm at my wit's end and I'm about to sign up for AT&T fiber if this problem doesn't get permanently resolved. I've heard nothing but horror stories about Spectrum via friends up in LA, so I might have to roll the dice on AT&T, even though I absolutely hate AT&T.