I need some help please, I am starting to have nightmares I work in a Community Learning Centre, unfortunately for them I am the only tech support they can afford (other than our service provider, who so far seems to be worse than me :D

We have just been supplied with Gfast internet, connected to the open reach modem > WAN to the Archer VR400 router in wireless router mode > Ethernet into switches > Server and Ethernet ports around the building. We have up to 40 computers, but not all on at the same time.

The router says it is connected to the internet and many computers can connect through wi-fi directly to the router. One or two computers can connect via Ethernet but if more try to connect all of the wired computers (domain and non domain) say no internet connection. Wi-fi computers still work. Cannot access the routers settings webpage when no internet is displayed. Can when it is on. It is intermittent, it will come on and off (over 10 times in 4 hours), but at that time I wasn't monitoring how many other computers were on

• IP in router changed to match gateway ID settings in servers.
• IPv6 disabled in router (after issues)
• We have domain and non domain computers. Have turned off and unplugged the server from the network - same issues on all computers.
• Works as is with the old service provider and have tried new cable (no problem with cable)
• Virtual server wont connect to CCTV (can access it within the network ok) I have only used basic port forwarding on our old Virgin router so I am not 100% sure I'm not missing something on this and haven't looked into it yet, as this doesn't work even when some of the wired computers do
• Wi-fi computers connected to Ethernet access points loose connection the same as the wired computers
• Scan to email on our printer won't work - External IP address updated in settings
• Switches can be managed, but are just plug in and play.

scenario

Left one computer on all night playing youtube video after disabling IPv6 and no disconnections on 2 wired computers for over an hour (thought the problem was solved)

Still connected in the morning (No new logs in Network profile/operational)

2 wired computers (non domain) and one domain computer on - no dropout

class comes in, about 8 wired domain computers turned on - No internet message.

Pulled out Ethernet and set wireless configuration to obtain DNS automatically (it usually points to server for AD) Internet works (within range of router)

Wired computers and wi- fi computers still no internet and didn't come back on. (switched back to old provider after a couple of hours)

I'm not in the centre at the moment to provide any logs/more information, and wouldn't know what might help, but can go and get them if needed.

If you have got this far then thank you - If you have any ideas or solutions then a BIG THANK YOU :)