Well, I can give you some numbers for the IPQ40XX (Asus RT-AC58U at 666 MHz and not the Full 716 MHz - with QCE enabled)
Note: All values are MiB/s! and not Mbit/s!
This is with the qcrypto/QCE active:
root@xbow:~# cryptsetup benchmark
# Tests are approximate using memory only (no storage IO).
[...] (PBKDF benchmark - not important)
# Algorithm | Key | Encryption | Decryption
aes-cbc 128b 63.7 MiB/s 63.3 MiB/s
aes-cbc 256b 55.5 MiB/s 55.4 MiB/s
aes-xts 256b 50.5 MiB/s 60.7 MiB/s
aes-xts 512b N/A N/A
The AES-XTS 512bit is not working with the QCE. But it is with software ciphers.
w/o crypto (aka unbind qcrypto via sysfs - this can be done at runtime)
# Algorithm | Key | Encryption | Decryption
aes-cbc 128b 11.1 MiB/s 11.9 MiB/s
aes-cbc 256b 8.0 MiB/s 9.0 MiB/s
aes-xts 256b 10.7 MiB/s 11.6 MiB/s
aes-xts 512b 8.9 MiB/s 8.9 MiB/s
Again, These are in MiB/s!
So even in software cipher manages aes-128-cbc @ 11.1 MiB/s. Which is 11.1 MiB/s * 8 Bits / Byte = 88.8 Mbits/s .
With Hardware-acceleration the aes-128-cbc @ 63.3 MiB/s is about 506.4 MBit/s.
If you have a reasonably easy way to check the VPN, I can provide the numbers as well. Since I expect them to be lower due to the overhead.
Edit: fixed units.