Intermittent Internet Speed Degredation

I pay for 1000mg internet speeds but for several months now I have had intermittent issues with degraded speeds usually in the 10-50mg range. Wired is generally 30-80mg. The issues seems to be the most prevalent at night but I have also seen this issue in the afternoon and several hours past midnight which would both be outside of the “peak hours”. I’ve restarted my gateway multiple times during each of the occurrences of this issue but the results stay the same and it usually takes hours/overnight or longer of waiting for this to magically resolve on its own. I’ve used the Xfinity agent to try and get help but it only points me to having a technician come out to my house. I am hoping to get some help here before paying a technician to come to my house.