Question AP mystery - How to know the mind of a router?

[merlysys]

Experimenting with 2 routers/APs (call them X and Y) and 4 hotspots.
Can connect to all 4 hotspots with laptop wifi

Turned off laptop wifi, now laptop (win 10) connecting to LAN port of router via cable
Placed an AP/router between laptop and hotspot...

X-Can connect to all 4
Y- Can connect to 2 of 4

When I goto the 2 failed hotspot's Connected Devices screen Y is shown as connected.
So in summary, can connect to all 4 with wifi and router X, can connect to all 2 with Y

All I did at router Y was
-Enable WDS bridging
-Y's survey showed hotspot, I selected it and entered password
-Disable DHCP
-I didn't even set a new LAN IP address
On laptop I reset ethernet connection
and it worked!

So why it won't work for the other 2?
I guess the block is inside Y... packets reach Y from those 2 hotspots but they cannot reach Y's LAN port
So I tried the following at Y...
-disabled UnUP
-set router's LAN IP to 192.168.0.2
On laptop I reset ethernet connection

No luck, then I...
went to the laptop 's TCP/IP and changed them to
IPv4 Address: 192.168.0.2
Subnet 255.255.255.0
Gateway 192.168.0.1

Instead of guessing what the cause is or trying this and that setting can I go into the hotspot or Y to see where the fault lies? What app can do that?

Can we upload images to posts?

 

[Ralston18]

Make and model routers?

To post images:

http://www.tomshardware.com/answers/id-2173703/post-images-tomshardware-guide.html

 

[merlysys]

Problem one is TP-Link WR941ND
Dlink cheap access point 1610 works ok

I didn't want to give those details as people jump to conclusions and assume things like chipsets not compatible etc.
That may be the case but I want a way to find out how to see what errors it is running into.

 

[SamirD]

I don't understand what you're connecting to what and how. Draw a network diagram and upload it and I'll tell you what's wrong.