TheEthyr

Seems pretty clear that they need to fix the connection. Whether the problem is at their end of the fiber connection or your end at the ONT, there’s no way of knowing. You need to keep calling them. Insist that they send out another tech.

Most consumer modem-routers speak DOCSIS, not MoCA, so you don’t want to get one. While you could probably find a ISP modem-router on eBay with MoCA, it would be more straightforward to buy standalone MoCA adapters and a WiFi Access Point.

You would connect one MoCA adapter between a LAN port on the Xfinity modem-router and the coax splitter. Then the other MoCA adapter between the coax splitter and WiFi Access Point.

You may want to replace the splitter with one that can pass frequencies up to 1675 MHz. A standard 1000 MHz splitter will work though speeds may be reduced.

Finally, it’s recommended to put a MoCA filter onto the input of the splitter to keep the MoCA signal confined to your house. If your Xfinity modem-router uses DOCSIS 3.1, a 2nd MoCA filter on the modem can ensure that the modem avoids using MoCA frequencies. Not all ISPs provision DOCSIS 3.1 to use MoCA frequencies, so the 2nd filter may not be needed.

I read that devices often have a minimum signal strength (~70db) before they decide to switch

Yes, that's correct. So long as the AP is using the same SSID and password as the router, devices should roam on their own. It's odd that this is not happening. It shouldn't matter, but put the router and AP on different Wi-Fi channels.

Maybe you didn’t change anything on the network but something may have changed on its own. A firmware update could have altered the network settings on a device, such as the MyQ Garage Hub. Maybe it changed its IP address and caused a conflict with the router’s IP address. You could check the IP address assignments in the router or the logs.

Assigning a subnet is something you do on a router or a Layer 3 switch. A Layer 2 switch doesn’t care about subnets as far as switching is concerned.

There's another variable here, which is the behavior that TCP and UDP flows have on each other. There are a number of TCP congestion management algorithms that have been developed over the years. This paper, for example, shows that BBR congestion control is very unfair to CUBIC. IOW, if one PC is using BBR and another CUBIC, the first PC will hog most of the bandwidth.

Similarly, QUIC, which is a UDP-based alternative to TCP originally developed by Google and used a lot by Chrome, is quite unfair to TCP as the images show.

Anyway, this is a bit off topic. The main point that the network is only as fast as the slowest link is correct.

As another person said, it's a Belling-Lee outlet. There are adapters to convert it into a F-type connector used by MoCA.

You would need to ensure that other, similar outlets are wired together through a splitter. The splitter should ideally be replaced with one that can pass frequencies up to 1675 MHz. Finally, you'd probably want to disconnect the aerial antenna to remove it as a source of interference.

Your upload seems a bit high. Do you have any IoT devices that talk to the Internet, such as a Ring doorbell?

I used to have a Wi-Fi controlled A/C plug to remotely turn on/off a light. I never measured the actual bandwidth but that thing sent a lot more data to the Internet than I expected. I was more worried about privacy, so I put it into its own VLAN. :-/

Gaming doesn’t use a lot of bandwidth. OP says the brother plays 20 hours a week. Let’s say 80 hours per month. It would require an average bandwidth of about 15 Mbps during those 80 hours to consume 600 GB. Possible? Yes, but unlikely, especially since he’s not streaming his games.

Sure.

IGMP snooping blocks the transmission of multicast packets to switch ports that have no listeners. This can benefit devices connected to the switch. It can even protect the router from receiving multicast traffic provided that the transmitting devices are connected to the switch.

If a transmitter is connected directly to the router, the router will flood it out on all other ports, including the port connected to the switch. But the switch may choose to not flood it on its other ports if there are no listeners.

The AC Lites don't have to be ceiling mounted. I have two Unifi AP sitting on shelves.

Getting a remote user into your LAN is basically accomplished by setting up a VPN server and having your friend use a VPN client to connect.

Tailscale and Hamachi are two popular VPN services. Tailscale has a free plan that allows something like 2 or 3 users, so you could use that.

You can also set up a VPN by hand using WireGuard or OpenVPN. WireGuard is very popular these days. Tailscale actually uses WireGuard under the covers. It just takes care of configuring it for you. Tailscale also provides extra features to deal with NAT.

I’ve never tried installing Tailscale on a mobile phone acting as a hotspot. It may work. Tailscale has extensive documentation on their website.

Alternatively, your router may have a VPN server that you can use.

Lastly, you can install a VPN server onto a computer. You’ll have to configure port forwarding on the router to allow remote address to the VPN server.

This is just the basics. You can find plenty of guides for any of these options.