Neither the RT-AC86U nor the RT-AX86U have 8 Ethernet Ports.
The router you want is the RT-AX88U. Or better (and probably cheaper, wait for a sale on them) the RT-AX86U + a cheap and cheerful 8+ Port 1GbE switch instead.
You can also add the switch to the RT-AC86U you bought, of course. But with a Gbps ISP connection today, I would not be putting money in an AC class router.
Again, the above assumes you need to buy a router today. If you can make do for a few more months, your possible (Wi-Fi 6E) purchase will be that much more valuable into the future, or at the very least, you will have saved some money from buying one of the same router choices today, but at a lower price.
For security, buy yourself a USB drive (Patriot Elite 128GB or larger is my suggestion, or even better, a UGREEN PCIe SSD external USB enclosure and a 128GB or larger PCIe m.2 SSD), and follow the guide below to get the drive prepared for amtm, Entware, a 2GB swap file and the following scripts. Skynet, Diversion (if you want adblocking on your network), Unbound, YazFi and ntpMerlin.
Just ignore the part where it says to 'install' amtm. That hasn't been needed since RMerlin firmware 384.15_0 when amtm was included as part of the firmware.
amtm Step-by-Step https://www.snbforums.com/threads/amtm-step-by-step-install-guide-l-ld.56237/#post-483421
amtm - the Asuswrt-Merlin Terminal Menu - Diversion
After setting up the USB drive in the proper file format the router expects, creating a swap file, installing Enware (via Diversion 'Lite', if you plan to use it), and enabling the disk checker script in amtm 'dc', you can hit 'i' to see what other scripts (including the scripts above) you want to install. Note that you can't install all of them together. Depending on the script, it may be one choice or another.