Disable the HWNAT to have a try.It seems the HWNAT sometimes will block the connection between switch.

I think it's a bug. 841ND DO NOT have this problem.

Openwrt and DDWRT will be better

I think your ISP may have some limits. You had better contact them first.

I think you need ask a refund to the seller.....Good luck!

480=8hours I thinks the DHCP is working fine...... I have noticed the wireless statistic. It's always 0...But lucky it won't affect me. The last problem I think the DNS may be not correct at first...