I have a 60Mbps internet connection and 20 devices on local network. Some packages, which I want to run on router are Adblock, mwan3, SQM, openvpn and ddns (may be more). Which router should I choose for main router and other for 5Ghz Repeater? Can you give me advice?
Looking at he specs, I would aim at putting the Mi R3G as the main router. It has slightly faster CPU, double the RAM and significantly larger FLA. Archer C7 is a good router, but FLA is relatively small, so you could easily run out of space if you are not selective about what packages you install.
Having said that, I should say that I don't have Mi R3G. The device page on the Wiki doesn't mention any known issue, bu you could also search the forum to see other user's impression.
But if you are going to flash / already flashed both routers anyway, then you could just make the Mi R3G as the router and Archer C7 as the repeater and give it a try.
Thanks for your information, but I search in forum and found that ArcherC7 have been optimized and more stable than MiR3G. MiR3G gets a problem with 2.4Ghz. Is it true?
And how about wifi signal, somebody has used two these devices, can share with me experience?
I an not sure of you are refereeing to the issue of 2.4 GHz conflict with USB 3.0, or of there is another thing.
If it's about that, then at least some of the issue isn't particular to this device. See this
if you experience it, you force the device to work as USB 2.0 by connecting it via USB 2.0 cable, or you could try a long USB 3.0 cable to Phoebe the device further from the router (or a better shielded one) in order to reduce interference. There are some other tips here and there on the forum.
This topic also has some useful posts. Xiaomi Wifi Router 3G - 18.06.x / Wifi issues 2.4GHz + 5GHz.
As for the WiFi signal, you could just put the two router in the same location (preferably different channels), install a software to measure WiFi signal (on laptop or mobile) and go around the house to see which one works better.
You could try the Archer C7 as the main router, sacrificing the slight difference in the CPU, and hoping that the RAM will be enough for your use, but depending on what packages you install, you may run out of FLA space. Archer C7 had only 16 MB while Mi R3G has 128 MB.