That is a really strange problem. Since you have the same problem with WiFi and Ethernet, the problem seems to stem from the WAN connection, i.e., the connection between the router and the modem. I would suggest:
Turn off Access Control on the router (at the router level) and see if there’s any difference.
Use a different Ethernet cable to connect the router to the modem
If the above does not make a difference, and you have an Ethernet hub/switch or another router around, put it in between the pcWRT router and your modem. Does that make a difference?
If the above options do not help, please send email to [email protected]. We’ll help you out.