Dual WAN woes

[N0_Klu3]

Hi all,

I have 2x PPPoE WAN connections.
For the most part they have been working perfectly fine for the last month, few niggles here and there.

Last week I got an alert during the night, one of the WANs was down. This wasn't true or it was just high packet loss or something, and then like 2mins later it was back and re-added to the gateway group.
But then when it was re-added anything that was using this line was just dead.
No sites would load, nothing would function.
Messed around for ages, called ISP they said its up but there is 1) No connection to us
So ended up putting in my ISP password again and boom now I have a connection, and then 2) OK we can see a connection but its not serving any traffic through it.

Disabling and re-enabling gateways eventually it worked.
Today the same thing. Just dead.
Right now I've just disabled the gateway that is causing me issues and working on 1 connection.

But I'd really like to get to the bottom of it as why it's not serving traffic even tho it says it's up.
fast.com was reporting I couldn't hit some servers which is accurate as it was only transmitting traffic through 1 link.

I don't know the best way forward now either, how do I get this 2nd WAN connection to actually function.
Obviously I've reset everything...
I've changed it now to instead of Gateway down for Packet Loss or High Latency, I've changed it to Member Down in the hopes of it not resetting the Gateways so much.

I really need both WAN connections functioning and functioning well... Can anyone help?