We currently have two blocks of IP address space, 195.224.206/24 and 193.193.186/23. Everything works fine from 195.224.206 but from 193.193.186 there are often problems [...]

Did you try registering a "route" object for 193.193.186.0/23 in the routing registry? That might improve connectivity to those addresses. At least from here (Switzerland) we don't see the announcement for 193.193.186.0/23 from our European transit provider, presumably because it is filtered out. swiCE1>trace 195.224.206.1 Type escape sequence to abort. Tracing the route to gatekeeper.olf.co.uk (195.224.206.1) 1 switch.ch.ten-155.net (212.1.192.169) [AS 8933] 4 msec 4 msec 0 msec 2 ch-se.se.ten-155.net (212.1.192.46) [AS 8933] 52 msec 52 msec 52 msec 3 sw-gw.nordu.net (212.1.192.154) [AS 8933] 52 msec 52 msec 52 msec 4 west-gw.nordu.net (193.10.252.133) [AS 2603] 52 msec 52 msec 52 msec 5 et0-llb-x-dg.DG1.core.rtr.xara.net (194.68.128.46) 92 msec 92 msec 92 msec 6 at0-0-llb-pvc202-dg1.TH1.core.rtr.xara.net (194.143.164.105) [AS 5519] 92 msec 92 msec 92 msec 7 fd1-0-0-llb-x-many.TH28.core.rtr.xara.net (194.143.163.36) [AS 5519] 92 msec 92 msec 92 msec 8 hs0-0-0-llb-th28.HE1.core.rtr.xara.net (194.143.164.166) [AS 5519] 92 msec 92 msec 96 msec 9 fd1-1-0-llb-x-many.HE2.core.rtr.xara.net (194.143.163.114) [AS 5519] 92 msec 96 msec 96 msec 10 fd5-0-0-llb-x-many.HE5.core.rtr.xara.net (194.143.163.115) [AS 5519] 96 msec 92 msec 92 msec 11 olf-avnet-router.olf.co.uk (195.224.74.230) [AS 5519] 104 msec 104 msec se0-xfs-d600-he5.aviators.cust.rtr.xara.net (195.224.219.105) [AS 5519] 96 msec 12 olf-avnet-router.olf.co.uk (195.224.74.230) [AS 5519] 100 msec 100 msec 100 msec 13 olf-router-01.olf.co.uk (193.193.186.254) 128 msec 168 msec 172 msec 14 gatekeeper.olf.co.uk (195.224.206.1) [AS 5519] 112 msec 120 msec 144 msec swiCE1>trace 193.193.186.1 Type escape sequence to abort. Tracing the route to gatekeeper.olf.co.uk (193.193.186.1) 1 swiEZ1-A0-0-0-8.switch.ch (130.59.33.26) 8 msec 4 msec 8 msec 2 swiEG1-F1-0-0.switch.ch (130.59.20.211) 4 msec 8 msec 4 msec 3 swiNY1-A5-0-0-1.switch.ch (130.59.33.2) 100 msec 100 msec 100 msec 4 39.atm4-0-0.GW3.NYC4.ALTER.NET (157.130.13.61) 104 msec 100 msec 100 msec 5 110.ATM2-0.XR1.NYC4.ALTER.NET (152.63.21.202) 100 msec 100 msec 100 msec 6 189.ATM2-0.TR1.NYC1.ALTER.NET (146.188.179.18) 104 msec 100 msec 104 msec 7 104.ATM5-0.TR1.DCA1.ALTER.NET (146.188.136.213) 104 msec 108 msec 104 msec 8 199.ATM7-0.XR1.DCA1.ALTER.NET (146.188.161.133) 104 msec 104 msec 108 msec 9 195.ATM9-0-0.GW3.DCA1.ALTER.NET (146.188.161.77) 108 msec 112 msec 108 msec 10 abovenet-dca-gw.customer.ALTER.NET (157.130.37.254) 108 msec 104 msec 108 msec 11 main1-core1-oc3-1.iad.above.net (209.249.0.18) 108 msec 272 msec 104 msec 12 u-net.customers.iad.above.net (209.249.97.37) 156 msec 200 msec 168 msec 13 195.102.254.61 [AS 5669] 180 msec 192 msec 156 msec 14 195.102.254.70 [AS 5669] 172 msec 160 msec 180 msec 15 195.102.208.214 [AS 5669] 184 msec 192 msec 188 msec 16 gatekeeper.olf.co.uk (193.193.186.1) 180 msec 192 msec 208 msec -- Simon.