Unfortunately, Virgin Media do not "support" VPN connections over the broadband network they provide for residential users. This might impact users trying to connect back to their office resources using software such as Fortigate Forticlient, Sonicwall Global VPN or Sonicwal SSL-VPN.
Here is a link to their Acceptable Usage Policy, and the relevant secion is Section 12:
Terms | Usage Policy | Virgin Media Ireland
"Section 12: Use of Virtual Private Network (VPN)"
"As stated above, the Virgin Media Services are for residential use only and we do not support the use of VPN. If we find you are using VPN we may instruct you to stop using it and you must comply with this request. This is in order to prevent problems with our network and other Internet users."