New to Plusnet - everything works except anything Google related

[#1]

Hello

just moved broadband from TalkTalk to Plusnet.  On the day of switch, nothing worked for 6 hrs, then got the go-ahead from Plusnet.  Changed the provider address etc on my Netgear router, and all works.   Streaming movies to the TV, wifi and ethernet all OK, repeater and printing all good.   Speed approx 15Mb. 

BUT:

nothing connected to Google works.  Using both Firefox ,or Safari, no Google search works, while Yahoo searches are OK.  Gmail can no longer be accessed by Thunderbird on my Mac, or Gmail app on ipad.

To me it does not make sense.   I have not changed any block on my router, and all was ok with the previous service.

Does not make sense to me.   Any suggestions?

Best wishes,

FDG , Sheffield

PS: even the Plusnet cashback URL does not work

[#2]

This is a mistery.  Today, 48hrs after the previous message, all is back to normal again.  I was planning to do a factory reset on the router at the weekend, but now no need (it appears).  Speed went down from 14mbps to 3 mbps though.