Okay, thanks for the power levels. Unfortunately nothing really amiss except for the T3 timeouts, so it looks like a fault at the Cabinet, rather than something at your property. Unless it's affecting many users, VM will not show this as an area fault. I've no idea about the regular spikes in your TBB monitor, so perhaps someone else can provide an insight.?
I would still stand by my suggestion of getting your own Wifi kit for your house when this issue of lost Sync and T3 timeouts are sorted. If you peruse the threads here for a while, most seem to be suggesting mesh solutions, whereas I use hard wired AP's instead. It's a personal choice depending on circumstances.