We recently came across an interesting problem that was causing the internet to disconnect at seemingly random times in a resident's apartment. These problems are frequently caused by electrical noise entering the cable system and less frequently by poor signal coming to the property. We started by inspecting the interior woring. All conections were good, splitters were of good quality, and unused outlets were properly terminated. This inspection didn't reveal any possible causes for the dropping internet. We checked the main tap for the property and found it to be in good condition and properly grounded. The modem status showed upstream and downstream power levels and signal to noise ratio within limits. We were left wondering what could be causing the intermittent connection issues that the resident was experiencing.
Having ruled out the possibility that noise was entering the system from the resident's wiring, we began to think about what else could be sending electrical noise into the system. The resident experiencing the problem only used the cable connection for internet and accessed all other services such as streatming and phone over the internet connection. As a result the resident had a main cable input connected directly to a modem which was then connected to wifi. There was nothing in the reseident's apartment that could be causing noise to enter the cable system. However, one possibility that we considered is that the electrical noise was originating from another apartment.
It turns out that our resident's issues were caused by a MoCA signal coming from somwere else. MoCA, short for multimedia over coax alliance, is a protocol that uses a customer's wiring to send data with the customer's premises. As a result, the signal is being injected into the wiring at the customer's location, as opposed to the signal from the cable company that flows into the customer's location. MoCA is used by various devices to provide a wired data connection using the existing buildig coaxial cable. When used, MoCA netoworks should always have a filter installed to prevent the signal from backfeeding into the cable system. In our resident's case, it is likely that a neighbor in the building or nearby has a MoCA device installed without a filter.
When we installed a MoCA filter on the resident's modem, the disconnect problems were solved.
We're now recommending that all apartments have a MoCA filter installed along the main internet line to prevent interference, even if MoCA devices are not being used in the apartment. In our resident's case, the noise that was causing the internet to drop was actually a MoCA signal from another user.