Question Bridge problems... After a few hours I have to reboot the secondary router

[LeoVIII]

So, i have a Sagemcom fast 3890 v3 provided by the ISP (yeah i know the hijack issue, but so far haven't suffered it, maybe it's already firmware updated) that is the "internet router", and i have a "bridge router", the TL-WR841ND v8 connected to my PC by a networking cable straight to my onboard Qualcomm Atheros AR8171/8175 PCI-E. Both router communicate through WiFi.
I've configured the WR841ND in WDS Bridge mode, with the same SSID and password, same channel and country as the Sagemcom, changed LAN ip to 192.168.0.2 (Sagemcom is .1) and disabled DHCP.
The DHCP is handled by the Sagemcom, and i've changed the range to 192.168.0.20-70.
The connection works pretty well, everything's fine until after a few hours of connection, my PC stops receiving internet access, the WR841ND stops bringing internet over its wireless network, so i have to reboot him and after that, everything goes back to normal, and this behaviour is on loop.
So, any ideas?

 

[LeoVIII]

I've noticed that WR841ND's bandwith was in Auto, and that was always setting a 40mhz bandwith. And the sagemcom is in 20mhz. Also, when WR841ND is on 40mhz, the Channel moves from what i put in the configs.
I put channel 4, but it moves to 6. If i put WR841ND on 20mhz only, it stays at channel 4, the same as the Sagemcom.
So im deducing that was the problem maybe, time will tell.