Slow speeds and suspected interference

Sadly the technician that came today was unable to find a solution to my problem. This one at least was not a contractor which helped. He did acknowledge there was an issue and that the issues I'm having are strange. I have to say he was actually awesome, stayed for 3 or so hours and tested everything with me. We tried different game and application launchers on my pc, my PS5, everything. Oddly enough, when my downstream isn't dropping to 30mb/s, which he did see, only the PS5 and Epic games launcher get the proper download speeds. Steam, Ubisoft, EA, Battle.net all got far far less than what the PS5 and Epic Games launcher were getting in terms of download speeds. He said the drops in the downstream could be a modem that has begun to fail, but when everything IS working right it is odd that only those two get what I'm supposed to be getting. I'm not sure where to go from here. He gave me a card and said to text him if it drops again. He also said he'd ask his supervisor to take a look when they get back from vacation but he wasn't even sure if that would get any type of helpful resolution.