When I was working till December (retired now), I was a systems/network architect in a very large network of 18.000 PCs plus 3 Supercomputers so I know what you are talking about. Thing is that the O.P. is not part of such networks so the point is kinda irrelevant. Updates inside networks don't (shouldn't) use the internet in the first place.
Either way, don't take my word for it. This is what one of the MS Software engineers, that worked on QoS, code said some time ago.
Additionally, as I wrote above, please do the test and set QoS bandwidth to 99.9%. if you are right then your internet will be limited to 0.1% which you can easily verify with an internet speed test. If you have 1 Mbit stream it should go down to 10Kbits.
Anyway, as I said my intentions were not against you personally and I hope they haven't been perceived as such. It was about the QoS setting only. I will stop here, cause this turns to be a chit chat irrelevant of the OP issue but I'm always free via PM to further talk about it.
As for the "service host:network service 5.3 Mbps", I explained above what that host is used for, and QoS has little to do with it, as it has to do with DNS lookups, IPsec, and similar services, which I'm sure you know how important those are. The bandwidth they use is almost zero compared, even in prolonged sessions (days).
On the other hand, if one thinks that QoS apps/settings are interfering with his/her bandwidth, there is a more elegant solution that doesn't require messing up with settings in registry or group policies. Just remove/deactivate the QoS packet scheduler. If later an admin changes his mind, just reactivate it.
Regards.