For the last week or so I've been constantly losing internet connection. 

When my internet works, on the ONT I see a yellow Power light, a yellow Optical light, and an orange LAN2 light. When it's not working, the Power light and Optical light are the same, but the LAN2 light is out.

It will work for several hours at a time, and then it will drop, and not come back for hours.

In my router logs it looks like this, just gaining and losing connection every minute or so:

Jul 10 13:45:07 WAN Connection: Fail to connect with some issues.
Jul 10 13:45:12 WAN Connection: WAN(0) link down.
Jul 10 13:45:52 WAN Connection: WAN(0) link up.
Jul 10 13:45:52 rc_service: wanduck 179:notify_rc restart_wan_if 0
Jul 10 13:45:57 pppd[7880]: pppd 2.4.7 started by admin, uid 0
Jul 10 13:46:02 WAN Connection: Fail to connect with some issues.
Jul 10 13:46:08 WAN Connection: WAN(0) link down.
Jul 10 13:46:18 WAN Connection: WAN(0) link up.
Jul 10 13:46:18 rc_service: wanduck 179:notify_rc restart_wan_if 0
Jul 10 13:46:18 pppd[7880]: Unable to complete PPPoE Discovery
Jul 10 13:46:21 pppd[7929]: pppd 2.4.7 started by admin, uid 0
Jul 10 13:46:21 pppd[7929]: Connected to 18:2a:d3:69:07:f0 via interface vlan10
Jul 10 13:46:21 pppd[7929]: Connect: ppp0 <--> vlan10
Jul 10 13:46:25 pppd[7929]: PAP authentication succeeded
Jul 10 13:46:25 pppd[7929]: peer from calling number 18:2A:D3:69:07:F0 authorized
Jul 10 13:46:25 pppd[7929]: local  IP address 203.yy.yyy.yyy
Jul 10 13:46:25 pppd[7929]: remote IP address 111.yyy.y.yyy
Jul 10 13:46:26 wan: finish adding multi routes
Jul 10 13:46:27 WAN Connection: WAN was restored.
Jul 10 13:46:43 zcip client: configured 169.xxx.xx.xxx
Jul 10 13:47:02 WAN Connection: Fail to connect with some issues.
Jul 10 13:47:07 WAN Connection: WAN(0) link down.
Jul 10 13:47:22 WAN Connection: WAN(0) link up.
Jul 10 13:47:22 rc_service: wanduck 179:notify_rc restart_wan_if 0
Jul 10 13:47:22 pppd[7929]: Connection terminated.
Jul 10 13:47:26 pppd[8221]: pppd 2.4.7 started by admin, uid 0
Jul 10 13:47:26 pppd[8221]: Connected to 18:2a:d3:69:07:f0 via interface vlan10
Jul 10 13:47:26 pppd[8221]: Connect: ppp0 <--> vlan10
Jul 10 13:47:29 pppd[8221]: PAP authentication succeeded
Jul 10 13:47:29 pppd[8221]: peer from calling number 18:2A:D3:69:07:F0 authorized
Jul 10 13:47:29 pppd[8221]: local  IP address 203.xx.xxx.xxx
Jul 10 13:47:29 pppd[8221]: remote IP address 111.yy.y.yyy
Jul 10 13:47:30 wan: finish adding multi routes
Jul 10 13:47:31 WAN Connection: WAN was restored.
Jul 10 13:47:47 zcip client: configured 169.xxx.xx.xxx
Jul 10 13:47:51 WAN Connection: Fail to connect with some issues.
Jul 10 13:47:56 WAN Connection: WAN(0) link down.
Jul 10 13:48:59 pppd[8221]: Serial link appears to be disconnected.
Jul 10 13:49:01 WAN Connection: WAN(0) link up.
Jul 10 13:49:01 rc_service: wanduck 179:notify_rc restart_wan_if 0
Jul 10 13:49:07 pppd[8546]: pppd 2.4.7 started by admin, uid 0
Jul 10 13:49:07 pppd[8546]: Connected to 18:2a:d3:69:07:f0 via interface vlan10
Jul 10 13:49:07 pppd[8546]: Connect: ppp0 <--> vlan10
Jul 10 13:49:12 WAN Connection: Fail to connect with some issues.
Jul 10 13:49:19 pppd[8546]: PAP authentication succeeded
Jul 10 13:49:19 pppd[8546]: peer from calling number 18:2A:D3:69:07:F0 authorized
Jul 10 13:49:27 WAN Connection: WAN(0) link down.

After a few hours of doing this it will eventually come back on its own without me doing anything, and stays back for a random amount of time (sometimes 5 minutes, sometimes several hours) before it starts this disconnect/reconnect cycle again. Restarting the router, or ONT, or both, has no effect. 

I tried changing the router to the 2degrees provided fritzbox, and tried changing ethernet cables, but it still keeps happening.

Does anyone know what would cause this? I don't know how to troubleshoot this further and 2degrees are impossible to contact.