The best answer is C. Insufficient bandwidth . The pattern in the question matters more than anything else. The company moved to a hosted VoIP and video solution , which means voice and video traffic now depend heavily on the site’s internet connection. The problems begin mid-morning and continue into the afternoon , which strongly suggests the link becomes congested during the busiest usage period of the day.

That also explains why users see dropped calls, broken video, and slow internet access all at the same time. Real-time applications like VoIP and video are very sensitive to delay, jitter, and packet loss. When bandwidth is limited or saturated, those services are usually the first to show noticeable symptoms.

The fact that remote users do not report the same issue is another major clue. If the application platform itself were failing, remote users would likely be affected too. Since the issue seems limited to the main site, the bottleneck is most likely the local office’s WAN or internet connection rather than the hosted service.

The other options are weaker. Roaming misconfiguration is more of a wireless mobility issue, signal degradation is too vague for this traffic pattern, and a miswired cable would not usually appear only during peak business hours. This points to insufficient bandwidth .