I don't want to be rude but the OP certainly asked a legit question, which is not the same as being discussed in the other thread. The other thread assesses "Cheap", which does not necessarily equal $200. I would say $200 is a bit on the higher end. I'm kind of in the same boat as the OP but I already own the R7800 but I would easily trade up for something with a bit more oomph. I raised a topic in which I asked what ipq806x vs bcm53xx devices are likely to receive LEDE attention and support, and I'd rather base my decision based on that.
To the OP, I would say that the R7800 is a nice device that should fit the bill for what you want. I cant answer for the dlna use case though. The current 17.01.2 is stable. there are still some kinks but it shouldn't interfere with your use case and your device will stay on 100% of the time without need to restart wifi etc. I would also take input from others who use bcm53xx devices and other ipq806x devices (EA8500?)
https://www.pcengines.ch/apu2.htm
Click the shop link to price it out configured your way or check for local dist.
About $200
NOTE: for dual band you need 2 wireless cards or use your current device as an AP
The nbg6817 offers two independent system installations (dualboot) with 4+64 MB (kernel + rootfs) each, the vendor firmware reserves 3.2 GB of the eMMC for streamboost and dlna.
While the BT Home Hub 5 type A is a very interesting device, it's in a completely different performance league compared to the afforementioned devices. Adblock and OpenVPN might easily push any of the existing lantiq devices to its limits, even more at higher WAN speeds. Also keep in mind that the initial flashing of the BT Home Hub 5 type A isn't exactly for the faint hearted (fine pitch soldering with a high potential for hard-bricking). While that doesn't make this router a bad choice (on the contrary, its unique selling point of an integrated and well supported VDSL modem might make it rank very high for many use cases), the user needs to be aware of the fine print and its performance limitations (it's a better modem, coping with simple routing requirements (at VDSL+vectoring workloads), than a top end router).