AC88U or AC68U for second router?

[unclebuk]

I have an AC68U (auto IP connection) as a dedicated VPN router connected to the LAN of an AC88U configured with PPPoE from the ISP modem. I connect devices to the AC68U to take advantage of geo-blocking afforded by use of VPN clients configured on the router. All seems to work ok up to this point. The WAN/IP warning on AC68U has stopped blinking for some reason...unsure why.

Question: which router should be doing what...ie:, should AC68U be connected to the modem or leave as is with AC88U connected to modem?? Are there any significant differences between these two routers that gives an advantage if I modify the configuration and switch the roles of the routers?

Both routers are running on up to date stock Asus firmwares.

I lack expertise in this and unsure how to maximize the set-up.

Thanks in advance for your input, suggestions, etc.

unclebuk

 

[RMerlin]

With its much faster CPU, the RT-AC88U is better suited to handle VPN duties.

 

[unclebuk]

With its much faster CPU, the RT-AC88U is better suited to handle VPN duties.

Alright then, thanks for that.
I thought they had identical processors?

 

[Wutikorn]

I thought they had identical processors?

http://www.snbforums.com/threads/rt-ac68u-rt-ac68p-rt-ac1900-rt-ac1900p.35759/
https://wikidevi.com/wiki/ASUS_RT-AC88U
Only RT-AC1900P has the same processor clock as RT-AC88U. But RT-AC88U still has twice the RAM.