Does Mikrtotek RB750GR3 router support DES? Any idea about which Mikrotek router with similar grade but support DES and MD5?

I think I confused on router model, the Router Model is Mikrotek 2011iL, running RouterOS v6.43.8, firmware updated to 6.43.8. When using vpn on this device, we have problem that vpn speed is only 2.7MB/s vs 10.8MB/s. Same problem also happened on Mikrotek Cloud Router Switch CRS125, are these model...

I'm using this switch and found that file transfer speed is dramatically drop while VPN is connected - 10.8MB/s vs. 2.7MB/s(vpn). Our RouterOS has been upgraded to Ver.2.9. Anyone can help me why this happened?