Strange behavior

[Kernal]

Hi

I have helped to configured a network to a friend.
He has a wireless network between his home and company and a pfsense firewall on both places.
The internet is connected to the home pfsense firewall.
The traffic to the internet travel through a vlan between his company and home on the wireless.

Everything has worked perfectly until now then the isp switched from PPOE to DHCP.

Now he can only surf on the internet from his home computer.
On his company computers he only can surf to some sites like Google.
He can ping all url but not surf to them.
Even ftp works.

If he connect the two pfsense firewalls directly with a cable it works again.

Does anybody here have any clue about what this could be ?

[hoba]

Sounds like an MTU issue to me. Try lowering the MTU at the WAN connection that has changed. Try something conservative like 1400 and go up from there until it breaks. Then go back one step.