PPPoE from Vdsl Bridged Modem not working

I have a site that used an RB750 for years on a Bridged VDSL modem. Recently it started to drop the PPPoE sessions.
I tried a new RB750G3 and had the same issue.
I then fitted a temporary Sonicwall with PPPoE on the WAN and it is stable.
I replaced the Sonicwall with a Cisco RV320 and I am having the same issues as with the MIKROTIK
Here are the Mikrotik logs
Oct/12/2018 09:38:03 pppoe,ppp,debug pppoe-out1: LCP lowerdown
Oct/12/2018 09:38:03 pppoe,ppp,debug pppoe-out1: CCP close
Oct/12/2018 09:38:03 pppoe,ppp,debug pppoe-out1: BCP close
Oct/12/2018 09:38:03 pppoe,ppp,debug pppoe-out1: IPCP close
Oct/12/2018 09:38:03 pppoe,ppp,debug pppoe-out1: IPV6CP close
Oct/12/2018 09:38:03 pppoe,ppp,debug pppoe-out1: MPLSCP close
Oct/12/2018 09:38:03 pppoe,ppp,info pppoe-out1: terminating…
Oct/12/2018 09:38:03 pppoe,ppp,debug pppoe-out1: LCP lowerdown
Oct/12/2018 09:38:03 pppoe,ppp,debug pppoe-out1: LCP down event in starting state
Oct/12/2018 09:38:03 pppoe,ppp,info pppoe-out1: disconnected
Oct/12/2018 09:38:03 pppoe,ppp,info pppoe-out1: initializing…
Oct/12/2018 09:38:03 pppoe,ppp,info pppoe-out1: connecting…
Oct/12/2018 09:38:13 pppoe,ppp,debug pppoe-out1: CCP close
Oct/12/2018 09:38:13 pppoe,ppp,debug pppoe-out1: BCP close
Oct/12/2018 09:38:13 pppoe,ppp,debug pppoe-out1: IPCP close
Oct/12/2018 09:38:13 pppoe,ppp,debug pppoe-out1: IPV6CP close
Oct/12/2018 09:38:13 pppoe,ppp,debug pppoe-out1: MPLSCP close
Oct/12/2018 09:38:13 pppoe,ppp,info pppoe-out1: terminating… - disconnected
Oct/12/2018 09:38:13 pppoe,ppp,debug pppoe-out1: LCP lowerdown
Oct/12/2018 09:38:13 pppoe,ppp,debug pppoe-out1: LCP down event in starting state
Oct/12/2018 09:38:13 pppoe,ppp,info pppoe-out1: disconnected
Oct/12/2018 09:38:13 pppoe,ppp,info pppoe-out1: initializing…
Oct/12/2018 09:38:13 pppoe,ppp,info pppoe-out1: connecting…
Oct/12/2018 09:38:23 pppoe,ppp,debug pppoe-out1: CCP close
Oct/12/2018 09:38:23 pppoe,ppp,debug pppoe-out1: BCP close
Oct/12/2018 09:38:23 pppoe,ppp,debug pppoe-out1: IPCP close
Oct/12/2018 09:38:23 pppoe,ppp,debug pppoe-out1: IPV6CP close
Oct/12/2018 09:38:23 pppoe,ppp,debug pppoe-out1: MPLSCP close
Oct/12/2018 09:38:23 pppoe,ppp,info pppoe-out1: terminating… - disconnected
Oct/12/2018 09:38:23 pppoe,ppp,debug pppoe-out1: LCP lowerdown
Oct/12/2018 09:38:23 pppoe,ppp,debug pppoe-out1: LCP down event in starting state
Oct/12/2018 09:38:23 pppoe,ppp,info pppoe-out1: disconnected
Oct/12/2018 09:38:23 pppoe,ppp,info pppoe-out1: initializing…
Oct/12/2018 09:38:23 pppoe,ppp,info pppoe-out1: connecting…

The Service provider wont support it. They only support their own modem.
Any idea’s why a Soniwall will work without a drop and the Mikrotik wont work?