Try to open website: http://connect.infinitymu.net/ if you can't open this site and you can open www.infinitymu.net then you should contact your internet provider and ask them that you cannot connect to our site (http://connect.infinitymu.net) and see what they will tell you. If you managed to open connect.infinitymu.net site then your connect button should start working without problems.
The usual case of "missing connect button" is server is offline. Now we know server is online so it must be your side.
Did you try redownloading / installing infinitymu files? Also it did work on your computer BEFORE this issue right? Or is this the first time your playing InfinityMU?
update your dns servers to google servers instead your internet provider google dns
primary dns: 8.8.8.8
secondary dns: 8.8.4.4
This way you would get the current IP of the server and your dns cache shouldn't stucked to some old of our IPs. Rememer this is just one of the solutions. Other might be to contact your provider and tell him if they blocked the IP of site's domain : http://connect.infinitymu.net
If you don't know how to update your DNS servers here's the procedure. Go to Control Panel >> Network Connections >> Local Area Connection >> Properties >> Internet Protocol (TCP/IP) >> Properties >> Click the Use following DNS server addresses.
Preferred DNS Server: 8. 8. 8. 8.
Alternate DNS Server: 8. 8. 4. 4.