Slow WiFi since June

Hi there! My WiFi connection has slowed since June. I’m using KPN Experia Box ARV7519 PSN. I ran a speed test using KPN website that gave 7.9 Mbps for the download and .4 Mbps for the upload. I suspect that it might be a street repair that happened next to my house in June. They’re still carving up streets but moved to an adjacent neighborhood. I think they might have dug up the optic cable which ruined the WiFi speed. But I think my theory is presumptuous and there’s gotta be a simple explanation as to why the WiFi slowed down. I appreciate anybody’s answers on a possible problem and a potential solution. Thanks!