..... I thought I'd try another ADSL2 router that I had previously on this connection some time ago (6 months?), had swapped it as it lost a LAN port (now 3 from 4 working). Swapped them out and ..... no problem....... all is ok.............. Swapped the original back in to run the diags/supply info requested above (to ensure accurate info supplied via same devices) and some of the original sites now connect ok. That was about an hour ago . Now, tested again as I type this and at least one site is unavailable again. Will post this, go back to secondary (older "3 port" ) router and retest, repost.
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So do I have a router issue here, and what would have changed (I've not changed any settings myself)? And, this does not explain how/why the Acer Win7 laptop connected ok where the other AMDWIN10device had issues.