As others suggest - get a small, 8 or 12 port switch. Feed a single port from the existing router into the switch and then connect everything to that. Let the switch do the work and not the router - leave that to manage the modem/DSL interface, firewall and DHCP server function. You may have to leave the WAP function on the router, or as I have done, three separate WAPs connected to the switch
A colleague and I did some experiments - he had four devices running off a router (server/NAS) and three PCs. Set various scripts running including a backup, web access, downloads &c and we watched the performance. A speedtest was running (to get a high data rate NOT to check the link speed) but the DSL link would not run at full speed (visual from TBB meter and task manager) - obviously the router was too busy to manage the full traffic flow.
We then left the server/NAS on the router and put the three PCs on a small switch - everything was fine until the backup started and that hogged the switch to router link and also caused the DSL data rate to drop as there was congestion on the router to switch link and data could not get from router to PC in a timely manner.
The third test was everything was connected to the switch and just a single switch to router link. The result was that the performance was better all round. It was possible to have the DSL link running at maximum for 10 to 20 minutes, the backup sped along &c &c.
M H C
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