I live in a kind of arrangement where several people share one Internet connection, including neighbors I hardly know who they are. We all have the password to one access point, router A.

I've never been too happy with that arrangement, so I installed two routers at my home, routers B and C. They can't be clients and access points at the same time, so router B is a wireless client to router A, while router C is hooked up to B through Ethernet cable and acts as my personal access point. All my machines/devices associate with router C.

That gives me these advantages:

- I associate with a router that is closer (C) therefore offers a better signal;
- I can share files to and fro my computer, tablet and phone more securely, since the files never go through router A;
- I guess I can browse more securely, since I am behind two/three routers.

The big drawback I am getting from it is that my connection becomes a lot slower, about 10% of the speed I get when associated to router A directly.

How can I troubleshoot this, i.e. find out which router is slow, and solve that?

Your adding an extra "hop" so to speak.

There is now another device that has to connect to another device via wireless and that is slowing it down. Not to mention, router A probably has some load balancing and if router A has a load from other users, there may be congestion.

I don't see any real solution to your problem.

The Internet is a series of hops. What is wrong with mine, is the question.

Wireless is not instant.

Other than general wireless bottlenecks, you might look into the DNS used by clients, and caching.

If the cleints are using router C's DNS which queries router B's DNS which queires router A's DNS... that might be a problem. You might change a client resolv.conf to use an external DNS, like 8.8.8.8 and see if that makes a difference.

The middle man for wifi in essence cuts your bandwidth in half, all things being equal. Also if you're bouncing C->B->A->ISP->A->B->C for every DNS inquiry that can slow you down. If the DNS server is incomplete / sucks you could be waiting on every one of those requests to timeout.

Other things to consider is that wireless signals like sound are directional. Keep those things verticle to the earth. My dads router was at a 45 degree wedged behind his monitor. I put a cup under it to level it out relative to the other cruft crowding it, and a 300ms ping went down to 2ms. And the now you see me, now you don't signal went to 58/70. Although everytime he used the microwave the wifi dropped.

What do you mean by "speed", when you say it drops to 10% of running on router A directly? Latency/ping? Steady state upload? Download? DNS requests? Try running a bandwidth test from dslreports.com or speedtest.net and compare all of the numbers that come out to see where the discrepancy lies.

Also, what are the manufacturer/models of router A, B, and C? You may be running into an issue of mixing standards. Maybe router A is capable of 802.11n/ac but router B and/or C can only do 802.11g. It could also be a simple wireless congestion problem, what bands are A/B/C running on (2.4 or 5 GHz)?