Currrently I am using a TP-Link TL-R480T+ router for dual WAN operation. Load Balancing and Link Backup for IPv4 with NAT is working fine but the IPv6 support of this router is unfeasible. I am only able to "bridge" one WAN port for IPv6 traffic to the LAN, so that all IPv6 traffic have neither Load Balancing nor Link Backup. The integrated DHCPv6 server is not powerful enough (no support for LUA, no omit of the global prefix etc.) For this device there is no OpenWrt firmware available and so I want to change my hardware.
I need the following features:
At least 2 WAN ports and 1 LAN port (both Gigabit Ethernet)
Load Balancing (if both WAN ports are available, use the entire bandwidth)
Link Backup (if only one WAN port is available, all traffic through that port)
IPv4 support with NAT
IPv6 support with NPTv6 (LAN clients using LUA and the gateway translates the local prefix with one of the global prefixes to achieve 2 and 3)
I do not need WiFi, USB, modem or so on...
I do not know OpenWrt well enough to be able to tell which functions the hardware has to support in order to realize the intended features.
Can anyone give me a recommendation for a suitable device?
This would be a good place for a MT7621 based device such as the Ubiquiti Edgerouter-X or Mikrotik RB750Gr3. They are well under 100 euros and have considerably more CPU than the R450 without getting into x86. The MT7621 is good for WAN speeds up to about 200 Mb.
Go with x86-64 (aka AMD64) if you want the easiest solution, Intel, Broadcom or Chelsio NICs will be all good and avoid Realtek. It's probably doable with OpenWrt (I think you'll need to make a few packages on your own however) but you might want to look at something else if you want more detailed logging etc unless you're willing to port more software.
I'm not a big fan of Realtek NICs either, but, at least those on the ODRIOD H2 I have on the bench, they seem to perform adequately for the price point. If you're regularly pushing close to gigabit rates through a single NIC, I'd second the recommendation for a "quality" NIC, if not a pair of them, bonded.
While 10GigE NICs are "affordable" (under US$50, plus the cost of optical cable and adapters), 10GigE switches are still in the US$500 and up range, such as for a used Dell 8024F. (No, I don't own one yet.)