Does Xfinity Gateway act as unmanaged switch in bridge mode?

My Xfinity XB8-T Gateway is in bridge mode. Switch port 4 (Orange) is connected to a Netgear RAXE300 wireless router/switch that provides a stronger and far superior Wi-Fi signal than the XB8-T did and completely solved a number of previously unresolvable connectivity issues with various Wi-Fi devices like door locks, wireless cameras, etc. Each of my three Xi6-A TV set top boxes are connected with an ethernet cable to the Netgear router's switch as ethernet has proven to me to work much more reliably than a Wi-Fi connection.

All three setup boxes work great except immediately after turning the TV and STB on. The set top boxes seem to take longer to start up and, without exception, provide an error message about an undefined but unexpected problem. Just acknowledging this dialog gets everything going OK. Nevertheless, every night we initially have error messages, no audio, etc. when starting a TV.

So, I tried an experiment and got an unexpected but good result. Instead of the Ethernet cables from each of the three set top boxes terminating in the Netgear wireless router's switch, I connected them to the unused ports on the XB8-T Gateway (in bridge mode). To my surprise, none of the startup glitches, I just described, occur anymore. Everything now starts up immediately and without a problem. Also, obviously, even though the XB8-T Gateway is in bridge mode, the integrated switch still works.

Although, I did not expect the XB8-T switch to work except for the orange port, it seems to work and work very well. However, does connecting the three set top boxes directly to the Gateway and its presumably unmanaged but functioning switch, present any security concerns for me? Is there anything else I do not know enough to ask about I should be aware of?