We have the same problem. Every afternoon around 1:30 pm our network disappears off the list of available networks. Your answer about faulty splitters makes sense to me. The Comcast/Xfinity tech who first installed our system told us that the previous owner left a mess of cables and splitters in the attic. He also said Xfinity was not interested in cleaning it up. I'm seventy and my husband is eighty. We don't want to take this job on. Where do we go for hired help if Xfinity says, "That's not our job."
You could try asking a local low voltage electrician to do it. Good luck !
Thanks. Will try to find an electrician who specializes in cable. Wish Xfinity would be more helpful and at least provide a list of capable contractors.