Hi
try by doing either of the below:
1. under WAN/MultiWAN section for each wan interface (1 & 2), edit and disable "Network Service Detection" feature completely
- and then each time do a apply and then do a permanent save to startup config (in Administration/Configuration Mgmnt)
OR
2. Go to the NSD gui page as mentioned above for each wan1 & wan2 interface AND
- instead of the present default setting of "Default Route/Gateway", set it to Remote-Host and give value of 8.8.8.8....
- 8.8.8.8/8.8.4.4 are public DNS servers of Google...and they are always UP and reachable on internet...
Do a apply and a permanent save AND
Reboot the router ONCE after either of the above changes (and after a permanent save)
Note: Additionally, it may also be becos of dns-resolutions failing intermittently...so for both wan interfaces, try by setting the dns1/dns2 to 8.8.8.8/8.8.4.4.....
- and in your dhcp-server configured for lan-hosts, check with selecting "Use Dns-Proxy".