[SOLVED] 100 Mbps Ethernet(2-pairs ) works with old router but not with new router(gigabit WAN) ?

[Aghor]

Ethernet(cat 5e) connector from my ISP is using only 1, 2, 3 & 6 pins. I connect to internet using PPPoE.
My old routers (TPLink C20 & Linksys E900) still detect this cable when plugged to WAN port. These old routers have fast-ethernet (100 Mbps) ports.
Couple of days ago I bought new router viz. D-link Covr-1100 which has gigabit ports. But this router is not detecting ISP's ethernet cable when plugged to WAN port.
I can set WAN port speed to Auto/1000/100/10 Mbps in Covr-1100. However it detects ISP's ethernet when I set it to 10 Mbps only.
So I have few questions regarding this issue:
1] Do gigbit routers only work with gigatbit ethernet OR at least require all 8 wires connected?
2] OR is this the issue with my router (or this particular model), and I need to replace (or change to a different model)?
3] with current setup, is there any adapter or hardware available that I can use to deceive the new router into considering that it is gigabit connector(but will work only at 100Mbps)
4] any other solution that could work

Additional info:
1] Similar issues have been reported by other people for different routers:
forums.dlink, community.netgear, amazon review
2] I have already asked the ISP to reset MAC id, so that is not the issue here.
3] The guys sent by my ISP don't know how to solve this issue. Ports on their switches has only 4 pins (not sure if it is true), so they cannot provide 8-pin connection. All they said is, it has been working for years now for so many customers so it should work with any good router.
4] I can connect to internet using old router and then connect new router's WAN port to old router's LAN port But this creates double NAT. And I am not knowledgeable enough to connect these routers in bridge mode if it is possible (& supported by routers). And what would be the consequences.
All net plan are 100mbps or less & I don't need the gigabit speed for now.

Any advice would be appreciated.
Thanks in advance.

 

[bill001g]

Gigabit ports will run on 2 pair cables. They should attempt to run gigabit and if that fails drop to 100mbps and if that fails drop to 10mbps. You almost never see 10mbps anymore but if you have older cables or cable that is not actually at least cat5 ethernet it will not run at 100mbps. If you are using cat3 telephone cables these are only rated to 10mbps but you seldom see these it has been more than 30yrs.

Some device tolerate poor quality cables better than others.

Buying a new cable likely is the simple solution rather than spending a lot of time on this. If the cable run though the wall and it is hard to replace you should consider replacing the ends since that is where most problem are.

 

[Aghor]

Gigabit ports will run on 2 pair cables. They should attempt to run gigabit and if that fails drop to 100mbps and if that fails drop to 10mbps. You almost never see 10mbps anymore but if you have older cables or cable that is not actually at least cat5 ethernet it will not run at 100mbps. If you are using cat3 telephone cables these are only rated to 10mbps but you seldom see these it has been more than 30yrs.

Some device tolerate poor quality cables better than others.

Buying a new cable likely is the simple solution rather than spending a lot of time on this. If the cable run though the wall and it is hard to replace you should consider replacing the ends since that is where most problem are.

Thanks for answering, I'll use this lead to solve the issue