My Internet provider just installed a 2,5/1Gbps Internet connection and I’ve asked the guys to run a couple of their fiber to connect my router (HP Prodesk with OPNsense) to my server. I didn’t know that the fiber is single mode and all the SFP+ sold used now seems to be all for multi mode fiber (www.bargainhardware.co.ukfor example). The cable is about 30m, can I use a 810nm SFP+ or is it definitely better to use a 1310nm?
As long as both ends are a matching pair you should be ok. Of they ran single mode fibre use single mode sfps.
Check out FS.com Plenty of options for plugables.