The shield pro 2019 is probably still the best overall, it's not perfect as there are some weaknesses due to the age of its chipset, but for all the common formats used in Movies and TV it works perfectly, especially if you are playing full remux files, not re-encoded compressed video. Kodi runs very well, Plex runs very well, Jellyfin is mostly perfect too, but has some limitations in the current version.
Yes it supports HDR10 (not10+) and Dolby Vision, which covers 98% of all 4K blurays and TV shows, anything HDR10+ just gets played in HDR10 compatibility mode, if you TV doesn't do DV it plays the HDR10 layer on 99% of files. There are some issues with HLG as it isnt properly supported but you don't come across that format all that often and there is usually an SDR or regular HDR version available, if your TV supports manually activating HLG then it works fine.
Yes there is a minor colour bug in some DV content, no it isn't the end of the world as some people make it out to be.
It is one of the only players that will give you full DTS:X and Dolby Atmos support, it has a very nice configurable upscaler for lower res content (AI upscale on low works excellently with minimal artifacts), it still has a lot going for it despite its age.
Also its easy to decrapify with ADB, you can easily configure third party launchers and other fun stuff.
You should consider upgrading to some kind of mesh system then. sure they aren't perfect, but even a basic 3 node kit could probably increase your throughput ten fold. If you want to use DDWRT or OpnSense or whatever you can still run it separately and route internet traffic or use it for your DHCP server.
To stream a 4K bluray remux rips on your Lan you need a solid 150mbit minimum between server and player to be reliable for example. I am hardwired all the way except for mobiles, but even on Wi-Fi I can easily pull 400-500mbit real world throughput through most of the house thanks to my Wifi6 setup with multiple APs