You may have a "gigabit LAN", but are you sure you have "gigabit internet"? (I'm not saying you don't have gigabit internet but the two are often confused & it's an important distinction!)
You really don't give a lot of information other than what your MINIX devices are & that you have a gigabit capable LAN &/or internet. Outside of those facts, there an a lot of variables to consider.
What are you using to test your LAN &/or broadband speeds?
Are you testing both Neo T5's & the U9-H from the same port(s) on the same router?
What other network hardware are you using such as ethernet switches?
Are you sure your ethernet cabling is up to spec? (I.e. are all of your ethernet cables Cat5E or better?)
Have you tried rebooting your entire network, including routers, switches, repeater's if applicable, etc.?
Do you have a large family all using broadband on a range of devices? If yes, have you set up any QoS to give priority to specific IP's, specific devices, or are you using a router with smart adaptive QoS to prioritise certain network traffic?
These are purely some examples to start with but when it comes to networking issues the list of potential bottlenecks or problem areas goes on & on lol
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The point is, it's virtually impossible for others to help you troubleshoot under such circumstances with such little information to go on.
Please be patient too!! We're ALL just starting out with the Neo T5's "in the grander scheme" so to speak
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